IIT - JEE · VISION 2000 CHEMISTRY 1 IIT JEE INORGANIC CHEMISTRY ALKALI METALS F The alkali metal...

Chemistry

588-A, Talwandi, KotaTel. : (0744) 2405510, 6450883

Website : www.vision2000kota.com

Inorganic

Developed by : P.Joy

IIT - JEE

Contentsu Important facts of Inorganic Chemistry

u Important Inorganic Processes

u Some Important Periodic Facts

u Reagents and Mixtures

u Physical Properties of Gases

u Some Important Compounds and Minerals

u Compounds and Uses

Exercise # 1(Increasing/Decreasing Order Problem)

Exercise # 2(Match the Columns)

Exercise # 3(True or False)

Exercise # 4(Fill in the Blanks)

Exercise # 5(Reasoning Questions & Answers)

Contents : S.No. Topic : Page No.

1. Important facts of Inorganic Chemistry 1 to 131

2. Important Inorganic Processes 132 to 133

3. Some Important Periodic Facts 134 to 137

4. Reagents and Mixtures 138 to 139

5. Physical Properties of Gases 140 to 141

6. Some Important Compounds and Minerals 142 to 145

7. Compounds and Uses 146 to 151

8. Exercise # 1

(Increasing/Decreasing Order Problem) 152 to 156

9. Exercise # 2 (Match the Columns) 157 to 160

10. Exercise # 3 (True or False) 161 to 173

11. Exercise # 4 (Fill in the Blanks) 174 to 192

12. Answer Key (Exercise 1 to 4) 193 to 206

13. Exercise # 5

(Reasoning Questions & Answers) 207 to 226

INORGANIC CHEMISTRY

VISION 2000 1CHEMISTRY

INORGANIC CHEMISTRYIIT JEE

ALKALI METALS

F The alkali metal ions are excessively hydrated. The smaller size of the ion, the greater is the degreeof hydration. The hydration radius of alkali metal ions decreases in the order

Li+ > Na+ > K+ > Rb+ > Cs+

This is the reason that Li+ in aqueous solution ionic mobility decreases in the orderCs+ > Rb+ > K+ > Na+ > Li+

However, in the molten state, the ionic mobility follows the decreasing order :Li+ > Na+ > K+ > Rb+ > Rb+ Cs+

F The solutions of alkali metals in liquid NH3 are blue due to the formation of solvated electron,

highly conducting in nature due to both the presence of solvated cation as well as solvated electronand are highly reducing in nature due to the presence of solvated electrons.

M ⇔ M+ + e–

M+ + xNH3 → M+ (NH

3)

x

e– + yNH3 → e– (NH

3)

y

M + (x + y) NH3 → M+ (NH

3)

x + e– (NH

3)

y

Ammoniated cation Ammoniated electron.

F The alkali metals are soft due to large sized Kernels.

F In the molten state Cs is a better reducing agent while in the aqueous solution (among alkali metals)Li is a better reducing agent. This is because of more of hydration.

Li + x H2O → Li+ (H

2O)

x + e–

F Both alkali and alkaline earth metals impart characteristic colour to the flame.

F Complexes of alkali metals. Alkali metal ions are weak complex forming ions and form reasonablystable complexes with bidentate and polydentate ligands such as salicyl aldehyde, β-diketones,nitrophenols and α-nitroso-β-napthols etc.

Poly dentate ligands such as crown ethers and cryptals form highly stable complexes with alkalimetal ions. The ligands are highly selective in complex formation.

IMPORTANT FACTS OF INORGANIC CHEMISTRY



Only that alkali metal ion which fits exactly into the available hole of the polydentate ligand formsstable complexes. The cations which are either two small or too big to fit into the hole would notform stable complexes. For example the hole in cryptate-222 is just of the right size for the K+ ionto fit whereas Li+ and Na+ ions are too small to make contact with the oxygen atoms of the ligands.On the other hand, Rb+ and Cs+ ions are too big in size to fit into the hole without causing strain.Thus K+ complex of cryptate-222 is thus most stable. Similarly Na+ complex of cryptate-221 ismost stable out of all the alkali metal ion complexes with high ligand. Cryptat and crown ethercomplexes are also called wrap around compounds.

F Lithium nitrate evolves NO2 and O

2 on heating while sodium and potassium nitrates

evolve only oxygen

4LiNO3 → 2Li

2O + 4NO

2 + O

2

2NaNO3 → 2NaNO

2 + O

2

F Among alkali metal carbonates, only Li2CO

3 on heating evolves CO

2 others do not.

Li2CO

3 → Li

2O + CO

2

F Among alkali metals, density increases down the group with the only exception thatdensity of K is less than that of Na.

F The basicity of oxides and hydroxides increases while moving down the alkali metalfamily. This is because the electropositive character of the metal increases.

F The alkali metal carbonate which is stored in the atmosphere of CO2 is Li

2 CO

3.

F Alkali and alkaline earth metals cannot be prepared by the reduction of their oxidesmethod because their standard reduction electrode potentials are less. However, theycan be prepared electrolytically.

F Biological function of Na +, K+, Mg 2+ and Ca 2+

(i) Na + and K+ ions are present in red blood cells.

The ratio of K+ to Na + in red blood cells of human beings is 7 : 1, and in cats anddogs 1 : 15. They help in developing and functioning of nerve cells.

(ii) Mg2+ are present in chlorophyll a greening colouring pigment in plants whichabsorbs light and is essential for photosynthesis. Magnesium also controls a largenumber of enzyme reactions.

(iii) Calcium is present in bones as phosphate and plays an important role in bone structure withageing.Calcium also plays an important role in muscle contraction.

F Lithium has the following important ores :(a) Lepidolite, (Li, Na, K)

2 Al

2 (SiO

3)

3 (F, OH)

2 containing 2 – 6% Lithium.

(b) Spodumene, Li Al(SiO3)

2 containing 4 – 6% Lithium

(c) Petalite, LiAl (Si2O

5)

2



(d) Triphylite, (Li, Na)3 PO

4.(Fe,, Mn)

3 (PO

4)

2

(e) Amblygonite, Li(AlF)PO4

F Sodium occures only in the combined state as :(a) Rock salt or sodium chloride, NaCl in sea water and in some inland takes.(b) Borax, Na

2B

4O

7.10H

2O in the crude form called tincal.

(c) Chile salt petre or cliche, NaNO3.

(d) Sodium carbonate, Na2CO

3.

F Potassium occurs in the combined state as :(a) Strassfurt deposits of Germany contain mainly carnallite KCl.MgCl

2.6H

2O;

Kainite K2SO

4.MgSO

4.MgCl

2.6H

2O; Schonite K

2SO

4.MgSO

4.6H

2O; Sylvine KCl;

Polyhalite, K2SO

4.MgSO

4.CaSO

4.6H

2O.

(b) Orthoclase, K2O.Al

2O

3.6SiO

2, mica, K[Al

3Si

3O

10 (OH)

2]

(c) Indian salt petre, KNO3

(d) Washings of sheep wool, residue left on carbonizing beet sugar molasses containspotassium salts.

F Rubidium occurs to the extent of 1% in the mineral Lepidolite and also in Strassfurtdeposits. Carnallite contains 9% rubidium chloride.

F Caesium occurs in Pollucite which is caesium aluminium silicate containing 30%Caesium. Caesium also occurs in Lepidolite.

F Lithium was discovered by Berzelius and Arfyedson in 1817 from minerals petaliteand spodumene.

F Sodium was first of all isolated by Davy in 1807 from fused caustic soda.

F Potassium was isolated in the metallic state first by Sir Humphrey Devy by theelectrolysis of fused KOH. Gay Lussac and Thenard obtained Potassium by heatingKOH with metallic iron.

F Rubidium and Caesium were discovered by Bunsen and Kirchoff in 1861.

F Lithium is a silvery white metal (m.p. = 453.5 K; b.p. = 1620 K). It's density is0.534 g/cm3 and it is the lightest of all the solid elements. It is softer than lead. It ismalleable and ductile.

F Lithium imparts carmine red colour to flame.

F Lithium is a good conductor of electricity and heat.



F The specific heat of lithium is 0.96 at 323 K and it is highest than any other element of group 1.

F Lithium finds use

(a) In the manufacture of alloys. Lead-Lithium alloy is used for bearings and electriccable sheathing. Zinc-aluminium alloy is similar to milk steel.

(b) LiAlH4, as a reducing agent.

(c) LiCl is used in air conditioning plants.

(d) As a deoxidizer in the purification of copper and nickel.

(e) Lithium citrate and Lithium salicylate are used for the treatment of gout.

(f) In glass and pottery manufacture.

F Sodium is a silvery white metal. It forms tetragonal crystals. It's density is 0.97 g/cm3. It melts at 370.8 K and boils at 1154.4 K. It is a good conductor of electricityand dissolves in liquid NH

3 to give intense blue colour.

F Sodium gives two bright lines in the yellow region of spectrum at 5890 Å and 5896 Å.

F Sodium finds use

(a) In the preparation of sodium peroxide, sodamide, sodium cyanide, tetraethyllead etc.

(b) Sodium amalgam is employed as a reducing agent.

(c) As a catalyst in the preparation of artificial rubber from isoprene.

(d) As a deoxidizing agent in the preparation of light alloys and some rare earthmetals from their oxides.

(e) Sodium hydroxide (NaOH) is used in the manufacture of soap, paper, artificialsilk, organic dye stuffs, in the petroleum industry for refining, for mercerizingcotton and as a laboratory reagent.

(f) Sodium carbonate (Na2CO

3), washing soda is employed in the manufacture of

water glass, NaOH, borax and soap powders. It is also used for the softening ofhard water, in laundary as washing soda and in the qualitative analysis for preparingsoda extract.

(g) Sodium chloride (NaCl), common salt in used as a preservative in packing andcuring of meat and fish. When mixed with ice, it is used to prepare freezingmixtures. It is also employed as a startng material for the manufacture of chlorine,HCl, Na

2CO

3, NaOH etc. Sodium chloride is also employed in the preparation of

pottery glaze and in the manufacture of soap by the process of salting out of soapinvolving common ion effect.

(h) Sodium sulphate (Na2SO

4) is used for the manufacture of sulphur dyes and for

removing hair from the hides.

(i) Sodium bisulphite (NaHSO3) and metabisulphite (Na

2S

2O

5) are used in the photographic

developers and as an antichlor. NaHSO3 is also used as a food preservative.



(j) Sodium sulphite (Na2SO

3) is used as a mild bleaching agent for silken and woollen fabrics and

as an antichlor after chlorine bleach.

(k) Sodium thiosulphate (Na2S

2O

3.5H

2O) also called hypo is used in photography

to dissolve excess of AgBr on the photographic plate for fixing of negative byforming the complex Na

3[Ag(S

2O

3)

2], in textile industry as an antichlor, in the

extraction of gold and silver from their ores, in the volumetric estimation of iodine(i.e., Iodimetory and Iodometry) and as a medicine.

(l) Sodium nitr i te (NaNO2) is used in the manufacture of azodyes and in the

qualitative organic analysis.

(m) Sodium cyanide (NaCN) is used in the extraction of gold and silver from theirores, in electroplating and as a germicide in agriculture.

(n) Monosodium phosphate , NaH2PO

4 is used in baking powders.

F Analytical tests for sodium are :

(a) A crystalline white precipitate is obtained when an aqueous solution of a sodiumsalt is treated with potassium pyroantimonate solution (K

2H

2Sb

2O

7)

K2H

2Sb

2O

7 + 2NaCl → Na

2H

2Sb

2O

7 + 2KCl

Sodium pyroantimonate

(white ppt.)

(b) An aqueous solution of sodium forms a yellow crystalline precipitate of sodiummagnesium uranyl acetate NaMg (UO

2)

3.(CH

3 COO)

9.9H

2O on treatment with

magnesium uranyl acetate.

Na + + 3UO2 (CH

3COO)

2 + Mg (CH

3 COO)

2 + CH

3COO– + 9H

2O B

NaMg (UO2)

3 (CH

3COO)

9.9H

2O

(Yellow ppt.)

F Potassium is a silvery white metal (m.p. = 336.2 K, b.p. = 1038.5 K). It is morereactive than sodium.

F Potassium is feebly radioactive and emits β -rays.

F Potessium has three isotopes : 19

K39, 19

K40, 19

K41. The first isomer predominant. The radioactivityof potessium is caused by isotope

19K40 which is present to the extent of 0.012.

F Potassium is used

(a) In high temperature thermometers as an alloy with sodium.

(b) In photoelectric cells.

(c) K2CO

3, Potassium carbonate (Pearl ash) is used in the manufacture of soft soap.

It is also used in washing wool. A mixture of K2CO

3 and Na

2CO

3 called fusion

mixture is used in charcoal cavity tests.

(d) KCl is used by the patients with high blood pressure.



(e) KBr is used in medicine as sedative. In photography, it is used for the preparation of sensitiveemulsion.

(f) KNO3, nitre or Indian salt petre is used in the manufacture of Gunpowder - a

mxture of nitre (6 parts), charcoal (1 part) and sulphur (1 part). It is also used inmaking flint glass, in refrigeration, in medicine, in pickling of meat and as afertilizer.

(g) KCN is used in metallurgy, electroplating, in the separation of Cu and Cd ornickel and cobalt.

(h) KCNS is used as an analytic reagent for testing Fe 3+ ions and for silver nitratetitrations by Volhard method using ferric alum as indicator.

(i) K2SO

4 is used as a fertlizer for tobacco and wheat.

F Analytical tests for potassium are :

(a) A solution of Picric acid gives a yellow precipitate with K+ ions.

K+ + (NO2)

3 C

6H

2 OH → (NO

2)

3 C

6H

2O–K+ + H+

Picric acid Potassium Picrate

(Yellow ppt.)

(b) With hydrochloroplatinic acid, H2PtCl

6, a yellow ppt. is formed.

2K+ + H2Pt Cl

6 → K

2PtCl

6 + 2H+

(Yellow ppt.)

(c) With sodium cobaltinitrite Na3 [Co(NO

2)

6], a yellow ppt. of Potassium

cobaltinitrite is formed.

3K+ + Na3 [Co(NO

2)

6) → K

3 [Co(NO

2)

6]

Potassium cobaltinitrite

(Yellow ppt.)

(d) With alcoholic solution of tartaric acid, a white crystalline ppt. of potassiumhydrogen tartarate is formed.

CH (OH).COOH CH(OH).COOH

K+ + | ———→ | + H+

CH(OH).COOH CH(OH).COOK

Tartaric acid (White ppt.)

F Amatol , an explosive, contains NH4NO

3 and 20% TNT.

F Ammonal, an explosive contains ammonium nitrate and aluminium powder.

F Micro cosmic sa l t, Na(NH4)HPO

4.4H

2O is used to detect coloured ions forming

coloured beads of orthosphosphates commonly known as microcosmic bead test.

Na(NH4)HPO

4 ———→ NH

3 + H

2O + NaPO

3

Glassy bead



CuSO4 ———→ CuO + SO

3

CuO + NaPO3 ———→ Cu NaPO

4

Blue bead

F Ammonium nitrite , NH4NO

2 on heating evolves N

2 gas.

NH4NO

2 heat → N

2 + 2H

2O

F Ammonium nitrate (NH4NO

3) on gentle heating forms nitrous oxide (N

2O) but detonates on

rapid heating.

NH4NO

3

Slow

heating → N

2O + 2H

2O

2NH4NO

3 Detonation → 2N

2 + O

2 + 4H

2O

F Ammonium chloride (NH4Cl) is used in soldering and tinning. Acid obtained by the

dissociation of NH4Cl dissolves the metallic oxide layer and thus cleanses the surface

and enables the solder to bite. It is also used in Leclanche cells, dry cells, dyeing,calicoprinting and in medicine.

F Electric eye used in televisions contains an alloy of caesium and silver.

F Sodium bicarbonate (NaHCO3) is used in baking powder, in medicines to neutralize

the acidity of stomach, in fire extinguisher and as Seidlitz powder in effervescentdrinks.

F Lithia water is chemically Lithium bicarbonate which is obtained by passing CO2

gas through Li2CO

3 solution.

Li2CO

3 + H

2O + CO

2 ———→ 2LiHCO

3

Lithium bicarbonate

F Analytical tests for Lithium

(a) Lithium imparts crimson red colour to bunsen flame.

(b) An alkaline solution of Lithium salt on treatment with sodium phosphate solutionforms crystalline precipitate of Lithium phosphate.

3LiCl + Na2HPO

4 + NaOH ———→ Li

3PO

4 B + 3NaCl + H

2O

(c) Lithium salt solution on treatment with (NH4)2CO

3 solution gives a white ppt. of

Lithium carbonate

2LiCl + (NH4)

2CO

3 ———→ Li

2CO

3 B + 2NH

4Cl

White ppt.

F The hydration radius of alkali metal ions decreases in the following order :

Li+ > Na+ > K+ > Rb+ > Cs+



F The standard reduction electrode potentials of alkali metal ions are given as under :Electrode Standard reduction electrode potential

Li +/ L i – 3.03 V

Na +/Na – 2.71 V

K + / K – 2.93 V

Rb + / R b – 2.93 V

Cs +/Cs – 2.92 V

F The first ionization energy of alkali metals in (KJ mole –1) are given below :

L i N a K R b C s F r

520 496 419 403 376 375

F The densities at 298 K (in g/cm 3) for alkali metals are given as under :


0.53 0.97 0.86 1.53 1.90 –

F The melting points and boiling points of alkali metals (in Kelvin) are summed upas under :


M . p t . 453.5 370.8 336.2 312 301.5 –

B . p t . 1620 1154 1038 961 978 –

F The atomic and ionic radius of alkali metals (in Pm) are given as under :


At. radius 152 186 227 248 265 –

Ionic radius 76 102 138 152 167 –

F The relative abundance in earth's crust (PPm) for alkali metals are given as under:


18 22700 18400 78 2.6 –

F Heat of atomization of alkali metals follows the decreasing order (KJ mole–1)

L i > N a > K > R b > C s

163.6 104.2 83.2 79.5 75.7

F Lattice energy of alkali metal salts decreases from Li to Cs. For example, for LiF(1032 KJ mole –1) and CsF (726 KJ mole–1)

F The heat of formation of fluorides, chlorides, carbides and oxides of alkali metalsdecreases in the following order.

Li+ > Na+ > K+ > Rb+ > Cs+



F The covalent character of alkali metal oxides decreases and ionic character increases in the order :

Li2O > Na

2O > K

2O > Rb

2O > Cs

2O

F Lithium burns in air to give monoxide Li2O; sodium forms peroxide Na

2O

2 and others form super

oxides of the type MO2.

F The super oxides of alkali metals contain a three electron bond which makes them paramagneticand coloured.

F The thermal stability of hydrides of alkal metals decreases in the order :

LiH > NaH > KH > RbH > CsH

F The thermal stability of carbonates of alkali metals increases in the order :

Li < Na < K < Rb < Cs

F Action of heat on the nitrates of alkali metals

(a) Lithium nitrate evolves NO2 and O

2

4LiNO3 ———→ 2Li

2O + 4NO

2 + O

2

(b) Other alkali metal nitrates form nitrites and O2 gas.

2MNO3 ———→ 2MNO

2 + O

2

F Alkali metal oxides (except Li2O) undergo disproportionation (self oxidation reduction) to give the

peroxide and metal.

2Na2O 670 K → Na

2O

2 + 2Na

F The nature of oxides formed by alkali metals are given below :

Alkali metal Oxide

Li Li2O, Li

2O

2

Na Na2O, Na

2O

2, NaO

2

K K2O, K

2O

2, KO

2

Rb Rb2O, Rb

2O

2, RbO

2

Cs Cs2O, Cs

2O

2, CsO

2

F The oxides of alkali metals are coloured in nature.

For example,

Li2O

2Na

2O

2K

2O

2Rb

2O

2Cs

2O

2

WhitePale yellow Orange Dark brown Yellow

F The thermal stability of hydroxides of alkali metals increases in the following order :

LiOH < NaOH < KOH < RbOH < CsOH

For example, LiOH decomposes at 1050 K while NaOH decomposes at 1570 K.



F The coordination number of CsCl is 8 while other alkali metal chlorides crystallize with coordinationnumber 6 in NaCl type structure.

F The colour rimparted by different alkali and alkaline earth metals to the flame of the burner aregiven as under :

Li Na K Rb Cs

Crimson red YellowViolet Violet Violet

Ca Sr Ba Ra

Brick red Crimson Apple green Crimson

F Na2CO

3 does not mpart any colour to the flame but NaCl does because the thermal ionization of

Na2CO

3 does not take place at the temperature of flame of the burner.

F The specific heat of alkali metals decreases in the following order :

Li > Na > K > Rb

0.942 0.293 0.17 0.08

F Lithium does not form sold bicarbonate LiHCO3 due to its lesser electro-positive nature.

F Alkali metals are usually extractred by the electrolysis of their fused metal halides and not by theelectrolysis of their aqueous salt solutions due to their lesser standard reduction electrode potentials.

F Sodium carbonate is prepared by the following processes :

(a) LeBlanc's process

(b) Solvay's process or Ammonia soda process.

(c) Electrolytic process.

F In Solvay's process, CO2 gas is passed through saturated brine (NaCl) solution when sparingly

soluble NaHCO3 separates out.

NH3 + H

2O + CO

2 ———→ NH

4HCO

3

NH4HCO

3 + NaCl ———→ NaHCO

3 B + NH

4Cl

The NaHCO3 formed above is calcined to form Na

2CO

3

2NaHCO3 heat → Na

2CO

3 + CO

2 + H

2O

F The reactions taking place at different stages during the manufacture of Na2CO

3 by Solvay's

process are given as under :

(a) 2NH3 + CO

2 + H

2O ———→ (NH

4)

2CO

3

MgCl2 + (NH

4)

2CO

3 ———→ MgCO

3 + 2NH

4Cl

or MgCl2 + 2NH

4OH ———→ Mg(OH)

2 + 2NH

4Cl



(b) Ammonia recovery tower

NH4HCO

3 heat → NH

3 + CO

2 + H

2O

2NH4Cl + Ca(OH)

2 ———→ 2 NH

3 + CaCl

2 + 2H

2O

(c) Calcination of NaHCO3

2NaHCO3 ———→ Na

2CO

3 + CO

2 + H

2O

F In electrolytic process for the manufacture of Na2CO

3 (Nelson cell) if CO

2 under

pressure be blown along with steam, caustic soda produced will further react withCO

2 to give Na

2CO

3.

2NaOH + CO2 ———→ Na

2CO

3 + H

2O

F Caustic soda (NaOH) is manufactured by the following two methods :

(a) Causticizing process. In this process, milk of lime is added to hot Na2CO

3 solution

when CaCO3 separates as a mud and NaOH remains in solution. This process is

called causticization.

Na2CO

3 + Ca(OH)

2 ———→ 2NaOH + CaCO

3 B

(b) Electrolytic process involving Nelson cell and Castner – Kellner cell. The basicprinciple involved in this process is that when an electric current is passed throughbrine (NaCl) solution. The following reactions are involved :

NaCl ⇔ Na + + Cl–

At Cathode 2H2O + 2e– ———→ H

2 + 2OH –

Na + + OH – ———→ NaOH

At anode Cl– – 1e– ———→ Cl

Cl + Cl ———→ Cl2

If NaOH and Cl2 so produced are allowed to come in contact, the following reaction takes place :

2NaOH + Cl2 ———→ NaCl + NaClO + H

2O

Hence, the necessity arose that NaOH and Cl2 should not come in contact with one

another. This is accomplished by separating the anode from the cathode by

(i) A porous diphragm as in Nelson cell.

(ii) The use of mercury as in Castner-Kellner cell or Kellner solvay cell.

F Nelson Cell is used for the preparation of NaOH. It consists of a cathode lined withasbestos and suspended in a rectangular iron tank. A carbon anode dips in brinesolution placed in the cathode. On passing electric current Cl

2 is evolved at anode and H

2 is evolved

at cathode. NaOH is slowly formed in the cell which discharges as a 10-12% solution of NaOHwith about an equal concentration of NaCl.

F Lithium is harder and lighter than other alkali metals.

F Lithium has high melting points and boiling points. It can be melted in dry air without loosingbrilliance.



F LiH is more stable than other alkali metal halides.

F Lithium oxide dissolves in water quitely while others do more energetically.

F Lithium hydroxide is sparingly soluble in water and is a weak base.

F LiOH decomposes at red hot

2LiOH ———→ Li2O + H

2O

Other alkali metal hydroxides sublime unchanged as M(OH)2.

F LiCl is deliquescent and is soluble in alcohol and pyridine.

F L i2CO

3 decomposes to Li

2O and CO

2. The size of Li + makes Li

2O lattice more

stable as compared to Li2CO

3. In case of other alkali metal carbonates the larger size

of the metal ion makes the M2O lattice less stable as compared to M

2CO

3 and they

do not decompose.

F Lithium does not react with acetylene to form lithum acetylide while other alkalimetals do.

F LiSH (Lithium hydrosulphide) is thermally unstable while those of other alkalimetals more stable.

F Li2CO

3, Li

3PO

4 and LiF are insoluble in water while the carbonates, phosphates

and fluorides of other alkal metals are soluble.

F Li2Si

6 (Lithium silicide), a dark violet, hygroscopic compound is formed when lithium

is heated with silicon.

F Lithium on heating with NH3 forms lithium imide, Li

2NH while other alkali metals form metal

amides MNH2.

F LiClO4 is more soluble in alcohol, acetone etc. due to more solvation of Li+ ion

while perchlorates of other alkali metals are insoluble.

F Li2SO

4 does not form alums while other alkali metal sulphates form.

F Complexing ability is more for lithium than other alkali metals.

F Among alkalimetal carbonates and nitrates, only Li2CO

3 and LiNO

3 are unstable

and decompose on heatng forming oxides.

F Gun powder (75% KNO3, 13% charcoal and 12% sulphur) on explosion gives the following

products :

2KNO3 + S + 3C Explosion → K

2S + N

2 + 3CO

2

The gaseous products also include, CO and N2 and the solid residue besides K

2S also contains

K2CO

3 and K

2SO

4.



F Potassium carbonate (K2CO

3) cannot be prepared by solvay's process because it's bicarbonate

(KHCO3) is quite soluble. The method involved in the extraction of K

2CO

3 is given as under :

Hydrated magnesium carbonate (MgCO3.3H

2O) is added to a cold and saturated solution of KCl

and the whole mixture is then treated with CO2. A sparingly soluble double salt

KHCO3.MgCO

3.4H

2O is formed. The double salt is heated with water when CO

2 gas is evolved

and MgCO3 is left as a residue. The mixture is filtered and concentrated when K

2CO

3 crystallizes

out.

MgCO3.3H

2O + CO

2 ———→ Mg (HCO

3)

2 + 2H

2O

2KCl + Mg (HCO3)

2 ———→ 2 KHCO

3 + MgCl

2

KHCO3 + MgCO

3 + 4H

2O ———→ KHCO

3.MgCO

3.4H

2O

———→ 2MgCO3.3H

2O

2KHCO3.MgCO

3.4H

2O ———

———→ K2CO

3 + 3H

2O + CO

2

F Both K2CO

3 and KHCO

3 undergo hydrolysis and show alkaline pH.

F Lattice energies of alkali metal fluorides (in KJ mole –1) are given as under :

L i F N a F K F R b F C s F

1035 908 803 770 720

F Lattice energies of alkali metal chlorides (in KJ mole –1) are given as under :

LiCl NaCl K C l RbCl CsCl

845 770 703 673 644



ALKALINE EARTH METALS

F Among alkaline earth metals, Be and Mg do not impart any characteristic colour tothe flame due to more ionization energies.

F The stability of the carbonates of alkaline earth metals increases in the order

BeCO3 < MgCO

3 < CaCO

3 < SrCO

3 < BaCO

3

F Be and Mg have hexagonal close packed (hpc) structure while Ca and Sr have facecentred cubic (fcc) structure.

F Although second I.E. for alkaline earth metals is more than the first even then alka-line earth metals only four M2+ ions due to more hydration and extra stable inert gasconfiguration of M2+ ion.

F Be2C on treatment with H

2O forms CH

4 while CaC

2 forms C

2H

2.

Be2C + 2H

2O → 2BeO + CH

4

Methane

CaC2 + 2H

2O → Ca(OH)

2 + C

2H

2

Acetylene

F (a) The solubility of hydroxides of alkaline earth metals in water increases while movingfrom Be to Ba. The Ksp values for alkaline earth metal hydroxides are given :

Hydroxide Be(OH)2

Mg(OH)2

Ca(OH)2

Sr(OH)2

Ba(OH)2

Solubility product 1.6 x 10–26 8.9 x 10–12 1.3 x 10–4 3.2 x 10–4 5.4 x 10–2

(b) The solubility of sulphates of alkaline earth metals decreases down the group. TheKsp value for the sulphates of alkaline earth metals are given below :

Sulphates BeSO4

MgSO4

CaSO4

SrSO4

BaSO4

Solubility product Very high H i g h 2.4 x 10–5 7.6 x 10–7 1.5 x 10–9

(c) The solubility of carbonates of alkaline earth metals decreases down the group.

F BeH2 is covalent while MgH

2 is partly covalent and partly ionic and the remaining

hydrides are largely ionic.

F BeCl2 in the vapour phase above 900ºC is monomeric ; below 900ºC in the vapour

exists as a mixture of monomer BeCl2 and dimer Be

2Cl

4 ; in the solid state, has a

polymeric structure and when dissolved in a coordinating solvent it exists as a monomer.



F Portland cement is essentially a mixture of dicalcium silicate (2CaO . SiO2), tricalcium

silicate (3CaO . SiO2), tricalcium aluminate (3 CaO . Al

2O

3) and tetracalcium

aluminoferrate 4CaO. Al2O

3 . Fe

2O

3.

F Setting of cement is an exothermic reaction. The setting of cement involves both thehydration of calcium aluminate and calcium silicate to form colloidal gels and pre-cipitation of Ca(OH)

2 and Al(OH)

3 by hydrolysis. The Ca(OH)

2 binds the particles of

calcium silicate together while Al(OH)3 fills the interstices rendering the mass hard.

(i) 3 CaO . Al2O

3+ 6H

2O → 3CaO.Al

2O

36H

2O

Tricalcium aluminate Hydrated colloidal gel of tricalcium aluminate

(ii) 3CaOSiO2

+ H2O → Ca(OH)

2 + 2CaO. SiO

2

Tricalcium silicate p p t .

(iii) 2CaO. SiO2

+ xH2O → 2CaO.SiO

2xH

2O

Hydrated colloidal gel of dicalcium silicate

(iv) 3CaO2Al

2O

3+ 6H

2O → 3Ca(OH)

2 + 2Al(OH)

3

p p t p p t

(v ) 4CaO.Al2O

3.Fe

2O

3 + 6H

2O → 3CaO.Al

2O

3.6H

2O + CaO.Fe

2O

3

Tetracalcium alumino ferrate

F Role of gypsum during setting of cement is to remove fast setting tricalcium aluminateand the setting process is slowed down.

3CaO.Al2O

3 + 3CaSO

4 + 2H

2O → 3CaO.Al

2O

3.3CaSO

4.2H

2O

Gypsum Calcium sulphoaluminate

The slow setting yields the colloidal gel which imparts much greater strength to theset mass. This order is just the reverse of what should be expected normally from theelectronegativities of halogens. This anomalous behaviour can be explained on thetendency of the halogen atom to back donate it's electrons to the boron atom. As aresult of back donation, the electron deficiency of Boron gets compensated and there-fore lewis acid character is minimum for BF

3.

F Anhydrous MgCl2 cannot be prepared by the simple heating of hydrated magnesium

chloride MgCl2, 6H

2O, as it gets hydrolysed to magnesium oxide

MgCl2 . 6H

2O heat → MgO + 2HCl + 5H

2O

F Gypsum on heating upto 390 K forms plaster of paris.

CaSO4 . 2H

2O 390 K → CaSO

4 .

12

H2O + 3H

2O

Gypsum Plaster of paris



When heated above 473 K it loses water of crystallization completely to form anhy-drous CaSO

4 (dead burnt plaster).

F Beryllium occurs as

(i) Beryl, 3BeO.Al2O

3.6SiO

2 containing 11-15% BeO.

(ii) Chrysoberyl, BeO.Al2O

3 containing 7% BeO

(iii) Phenacite, Be2SiO

4

(iv) Brommelite, BeO

F Some important minerals of magnesium are

(i) Magnesite, MgCO3

(ii) Dolomite, MgCO3.CaCO

3

(iii) Epsomite or Epsom salt, MgCO3.7H

2O

(iv) Carnallite, KCl MgCl2.6H

2O

(v) Kieserite, MgSO4.H

2O

(vi) Kainite, K2SO

4.MgSO

4.MgCl

2.6H

2O

F Some important ores of calcium are given as under :

(i) Carbonate ores nclude Limestone, iceland spar, marble, chalk and dolomite,CaCO

3.MgCO

3.

(ii) Sulphate ores include, Gypsum, CaSO4.2H

2O and anhydrite CaSO

4.

(iii) Fluoride ores include, Fluorspar, CaF2 and fluorapatite, Ca

5 (PO

4)

3F.

(iv) Phosphorite, Ca3(PO

4)

2

(v) Chlorapatite, Ca5 (PO

4)

3 Cl

(vi) Silicate ore, CaSiO3, a constituent of rocks.

F The important ores of strontium are

(i) Strontianite, SrCO3.

(ii) Celestine, SrSO4.

F Barium occurs as ;

(i) Barytes or Heavy spar, BaSO4

(ii) Witherite, BaCO3

F Radium is widely distributed throughout the earth's crust and is also present in seawater and oceans. It is also found in almost all rocks in traces. All uranium metals,e.g., Pitch blende contains radium. Carnotite which contains K, U, V and Ra isobtained mainly from Belgian Cango.



F Beryllium is mainly used

(i) For makng electrode of neon signs and windows of x-ray tubes.

(ii) Because of low neutron cross-section it may possibly be used as canning metal for reactor fuel.

(iii) In the manufacture of alloys mainly with copper.

F Magnesium is mainly employed ;

(i) In flash light photography, signal fires, pyrotechnics and in fireworks.

(ii) In the manufacture of alloys e.g., (a) Magnalium (Al, 85 to 99%; Mg 1 to 15%) used formaking balance beams and light instruments (b) Electron (Mg, 95%, Zn = 5%) is used in theconstruction of aircraft.

(iii) As a reducing agent in the prepaation of B and Si and deoxidizer in metallurgy and as a fuse inalumino thermic process.

F Calcium finds use

(i) As a drying agent for the preparation of absolute alcohol.

(ii) In the removal of sulphur from petroleum.

(iii) In the preparation of Be, Cr and Th by the reduction of their oxides.

(iv) For removing last traces of air from noble gases.

(v) For obtaining vaccum.

(vi) For the removal of last traces of dissolved oxygen, nitrogen and sulphur from the metals duringextraction.

F Strontium finds practically no use. It's use in photoelectric cells has been suggested.

F Barium finds use only in some alloys.

F The atomic radius of group 2 elements (in Pm) are given as under :

Be Mg Ca Sr Ba Ra

105 162 197 213 217 –

F The first three ionization energies of group 2 elements (in KJ mole–1) are given as under :

Be Mg Ca Sr Ba Ra

894 734 587 547 500 508

1748 1443 1140 1059 960 962

14784 7691 4909 4130 3423 –

F The standard reduction electrode potentials of group 2 elements are

Be Mg Ca Sr Ba Ra

– 1.85 V – 2.34 V – 2.87 V – 1.89 V – 2.90 V – 2.92 V



F Electronegativities of group 2 elements in the decreasing order are given as under :

B e M g Ca S r B a

1.50 1.20 1.10 1 0.90

F The enthalpy of hydration of group 2 elements (in Kcal mole –1) are given as under:

B e M g Ca S r B a R a

570 460 395 355 305 –

F Melting points of group 2 elements (in K) are given as under :


3043 1380 1710 1639 1790 1413

F The colour imparted to the flame of burner by group 2 elements are given as under:


– – Brick red Crimson Apple green –

F The densities of group 2 elements (in g/c.c.) at 298 K are given as under :


1.86 1.75 1.55 2.60 3.39 5.5

F The relative abundance in earth's crust of group 2 elements (in PPm) is given asunder :


2 27640 46668 384 390 10–6

F The boiling points of group 2 elements (in K) are given as under :


2773 1378 1767 1654 2173 1973

F Salts of group 2 elements are more hydrated than those of the element of group 1e.g. ,

MgCl2.6H

2O; CaCl

2.6H

2O; BaCl

2.2H

2O

F Be is resistant to the attack of conc. HNO3 due to the formaton of an inert oxide

layer on it's surface.

F Beryllium forms beryllate on heating with conc. NaOH, and evolves H2 gas.

Be + NaOH + H2O ———→ Be (OH) ONa + H

2

Sodium beryllate



F Out of the oxides of group 2 elements only BeO is extremely hard, non volatile, hashigh melting point and is amphoteric.

F Beryllium carbide undergoes hydrolysis with water to produce CH4

Be2C + 4H

2O ———→ 2Be(OH)

2 + CH

4

F BeH2 and MgH

2 are polymeric solids and contain chains of the form with hydrogen

bridging.

F BeF2 and BeCl

2 are covalent due to smaller size of Be2+ ion and do not conduct

electricity in their molten state.

F BeCl2 is monomeric in the vapour state and it's dipole moment is zero suggesting it

to be linear molecule. In the solid state it is polymeric.

F BeF2 and BeCl

2 are hygroscopic and fume in moist air due to hydrolysis.

F Be is prepared by the reduction of it's oxide.

BeO + C ———→ Be + CO

F Berryllia crucibles are made from BeO.

F Solutions of Be salts give a blue coloration with Quinalizarin reagent (0.05 g

quinalizarin in 100 ml. N10

NaOH)

F Beryllium is estimated gravimetrically.

(i) As BeO (ii) As ammonium beryllium phosphate.

F Magnesium oxide (MgO) is used.

(i) As a refractory lining in electric furnaces.

(ii) In medicine.

(iii) As a basc lining in smelting process of metallurgy.

(iv) As an insulator when mixed with asbestos for lagging steam pipes and boilers.

(v) As a rubber filler.

F Magnesum peroxide (MgO2) is used as an antiseptic in tooth pastes.



F Magnesium chloride (MgCl2.6H

2O) is used for making Sorel's cement (MgCl

2.5MgO.xH

2O) and

in cotton dressing.

F Anhydrous magnesium chloride (MgCl2) cannot be prepared by heating MgCl

2.6H

2O.

since on heating, MgCl2.6H

2O undergoes hydrolysis with the evolution of HCl gas.

MgCl2.6H

2O heat → Mg(OH).Cl + H

2O

F Magnesium per chlorate [Mg(ClO4)

2] is used as a drying agent under the trade name

Anhydrone.

F Epsom salt (MgSO4.7H

2O) is used mainly

(i) As a purgative.

(ii) In tanning and dyeing processes.

(iii) Catalyst in Grillo's process for the manufacture of H2SO

4.

F Analytical detection of Mg

(i) Charcoal cavity test. On heating on a charcoal cavity with one drop of CO(NO3)

2,

a pink colour is imparted to the residue.

(ii) The salt solution when mixed with NH4Cl and NH

4OH and finally treated with

soluble phosphates forms a white precipitate of magnesium ammonium phosphate.

MgSO4 + Na

2HPO

4 + NH

4OH ———→ Mg(NH

4)PO

4 + Na

2SO

4 + H

2O

White ppt.

F Calcium oxide (Quick lime, CaO) is used

(i) In the manufacture of CaCl2 cement, mortar, glass.

(ii) For drying gases and alcohol.

(iii) As a basic lining for furnances.

(iv) As slaked lime for the manufacture of NaOH, Na2CO

3, CaOCl

2 and basic

Ca(NO3)

2

(v) As milk of lime in white washing and refining of sugar.

(vi) For preparing NH3 and soda lime.

F Mortar is a mixture of slaked lime, sand and water. Function of sand in mortar is tomake the mass more porous, harder and to prevent excessive shrinkage which mightresult in cracks.

F Calcium peroxide (CaO2) is formed when Ca(OH)

2 is treated with H

2O

2. It is used

for bleaching and antiseptic purposes.



F Calcium carbonate (CaCO3) is used

(i) For the preparation of lime, cement, washing soda, glass.

(ii) In the form of marble for building purposes.

(iii) In the form of chalk in paints, tooth pastes and powders.

(iv) In the form of lime stone as flux.

F Calcium chloride (CaCl2.6H

2O) is used

(i) For dry gases and liquids (but not alcohols since they form addition products i.e.,alcoholates)

(ii) It is sprinkled on roads to keep them wet and prevent dust from flying.

(iii) In making freezing mixtures and in refrigeration.

(iv) In liquid baths for heating purposes.

F Hydrolith (CaH2) is calcium hydride.

F Calc ium cyanamide (CaCN2) is prepared by heating a mixture of CaC

2 in an

atmosphere of N2 at 1270 – 1370 with CaF

2.

CaC2 + N

2

CaF

K2

1270 1370 →

− CaCN

2 + C

Its trade name is Nitrolim.

F Calcium cyanamide (CaCN2) is a slow acting manure and is preffered to soluble

compounds like NaNO3 or (NH

4)

2 SO

4 since it confers fertility of a permanent

nature. It is a nitrogeneous fertilizer and undergoes a series of changes givingcyanamide, urea, NH

3 and finally the nitrates which are assimilable by plants.

CaCN2 + H

2O + CO

2 ———→ CaCO

3 + H

2NCN

H2NCN + H

2O ———→ H

2NCONH

2

Urea

H2NCONH

2 + H

2O ———→ CO

2 + 2NH

3

F Calcium cyanamide (CaCN2) is used in case hardening of steel.

F Calcium carbide (CaC2) is mainly used

(i) As a source of acetylene in oxyacetylene flame.

(ii) In the manufacture of calcium cyanamide.

F Norwegian salt petre is a mixture of lime and Ca(NO3)

2 and has the composition

Ca(NO3)

2.CaO



F Super phosphate of lime is a mixture of

Ca(H2PO

4)

2.H

2O and 2CaSO

4.2H

2O

F Triple super phosphate is chemically Ca(H2PO

4)

2.

F Gypsum (CaSO4.2H

2O) looses water on heating at 325 K to form plaster of paris

CaSO4.

12

H2O or 2CaSO

4.H

2O. However, when heated strongly it looses whole of

it's water of hydration to form dead burnt plaster. It does not set like plaster ofparis.

F Plaster of paris (CaSO4.

12

H2O) is used

(i) In making casts and moulds.

(ii) In surgery for plastering fractured parts of the body and for preparing blackboardchalks.

(iii) In agriculture for impregnating filter papers.

F Flow free salt contains a small amount of Ca3(PO

4)

2 mixed to NaCl.

F Baking powder is a mixture of NaHCO3 and Ca(H

2PO

4)

2

F Portland cement is a dirty greenish, heavy fine powder which is essentially a mixtureof various silicates and aluminates of calcium, chiefly, tricalcium silicate, 3CaO.SiO

2;

tricalcium aluminate, 3CaO.Al2O

3; dicalcium silicate, 2CaO.SiO

2 and tetra calcium

aluminoferrate 4CaO.Al2O

3.Fe

2O

3

The average composition of portland cement is

C a O 62%

SiO2

22%

Al2O

37.5%

M g O 2.5%

Fe2O

32.5%

SO2

1.5%

Na2O 1%

K2O 1%

F Analytical detection of calcium

(i) Flame test. A brick red colour is mparted by the paste of the salt in conc. HCl andthe colour is invisible through blue glass.



(ii) With ammonum oxalate, a white precipitate of calcium oxalate is obtained which s soluble indilute HNO

3 but nsoluble in CH

3COOH.

CaCl2 + (NH

4)

2C

2O

4 ———→ CaC

2O

4 + 2NH

4Cl

Calcium oxalate

(White ppt.)

F Strontia is chemically strontium oxide (SrO)

F Red fires are observed by using Sr (NO3)

2

F Analytical detection of strontium

(i) Flame test. A pase of strontum salt in conc. HCl imparts crimson colour to theflame which is visible through blue glass.

(ii) With CaSO4 solution, it gives a white precipitate of SrSO

4.

CaSO4 + Sr2+ ———→ SrSO

4 + Ca 2+

White ppt.

F Baryta (BaO) is obtained by the decomposition or Barium nitrate or hydroxide tored hot.

F [Be(H2O)

4]2+ is an acid.

F [Be(OH)4]2– is a base.

F BeO is covalent and has wurtzite (4 : 4) structure while other normal oxides ofgroup are ionic and have sodium chloride type (6 : 6) structure.

F CaF2 has dispersion and transparency properties so it is used in prisms of

spectrometers.

F In the elementary state, both Be and Mg crystallize with a hexagonal crystal lattice.In this structure:

(i) There is hexagonal closed packing of spheres. Hence the interstitial space betweenthem is minimum.

(ii) Each unit cell contains two atoms because each of the corner is common to 8unit cells.

F In elementary state, both Ca and Sr crystallize with a face centred Cubic structure.In this structure :

(i) Each Ca atom has 12 neghbours at equal distance of 3.34 Å.

(ii) Each Sr atom has 12 neighbours at equal distance of 3.48 Å.



F In elementary state, Ba crystallizes with body centred cubic structure. In this structure.

(i) Each Ba atom has 8 neighbours at equal distance of 4.34 Å

(ii) The spheres occupy 68.02% space in this structure.

F Green fire involves the use of Barium chlorate, Ba(ClO3)

2.

F Barium is quantitatively estimated as Barium chromate with (NH4)

2CrO

4 solution

at pH 5.7.

Ba2+ + CrO4

2– ———→ BaCrO4

F Complexometr ica l l y barium soluton is titrated with EDTA using the indicatormethylthymol blue at pH 12. The colour change from blue to green shows the endpoint.

F Radium and it's salt are used in medcines as a source of alpha rays. Small amountsof radium bromide have been used for luminous coating of watch dials and air craftinstruments.

F The electronegativity values of s and p-block elements are given as under :

Group → 1 2 13 14 15 16 17 18

Period B1 H H e

2.1 0

2 L i B e B C N O F N e

1.0 1.5 2 2.5 3.0 3.5 4.0 0

3 Na M g Al S i P S Cl Ar

0.9 1.2 1.5 1.8 2.0 2.5 3.0 0

4 K Ca G a G e A s S e B r K r

0.8 1.0 1.6 1.8 2.0 2.4 2.8 0

5 R b S r l n S n S b T e I X e

0.8 1.0 1.7 1.8 1.9 2.1 2.5 0

6 C s B a T l P b B i P o At R n

0.7 0.9 1.8 1.8 1.9 2.0 2.2 0



d-BLOCK

F The f-block elements differ from those of d-blocks elements in that they have unsta-ble electronic configuration in the outer three shells in comparison to that of d-blockelements.

d-block elements electronic configuration

(n - 1) d1 – 10 ns1 – 2

f-block elements electronic configuration

(n - 2)f1 – 14 (n - 1) d0 – 1 ns1 – 2

F The most important ore of Lanthanide is monazite sand which contains phosphatesof La, Ce, Pr, Nd, Sm and thoria, ThO

2.

F The most common oxidation state of Lanthanides is + 3.

F The magnetic properties of d-block elements are due to the only spin value of theunpaired electrons present in d-orbitals while in case of f-block elements it is due toboth the orbital motion as well as spin contribution.

Magnetic moment for d-block elements : µ = n n( )+ 2 B. M.

(where n is the number of unpaired electrons)

Magnetic moment of f-block elements : µ = 4 1 1S S( ) ( )+ + +l l

(Where S is sum of spin quantum number and the l the angular momentum quan-tum number)

F The colour in d-block elements is due to d-excitations while in f-block elements, it isdue to f-f transitions.

F The elements with n number of f-electrons have a similar colour to those of (14 - n)f electrons.

F Lanthanide contraction is the slow or gradual decrease in size of lanthanide atomsand ions as we move from left to right in a lanthanide series.

The improper shieding of the increased nuclear charge by the f-electrons present in (n- 2) f subshell is the cause of Lanthanide contraction.

F Zr and Hf ; Nb and Ta ; Mo and W have similar properties due to Lanthanide con-traction.



F Zn, Sn and Al react with caustic soda to evolve H2 gas.

Zn + 2NaOH → Na2 Zn O

2 + H

2

Sodium Zincate

Zn + 2 NaOH → Na2 SnO

2 + H

2

Sodium stannite

2Al + 2 NaOH + 2H2O → 2Na AlO

2 + 3H

2

Sodium meta aluminate

F Ferrochrome contains nearly 75% chromium and is prepared by reducing chromiteore with

Carbon in an electric furnace

FeO.Cr2O

3 + 4C → Fe + 2Cr + 4CO

Ferrochrome

F Chromic acid mixture contains K2Cr

2O

7 and conc. H

2SO

4

F Chrome red is chemically basic lead chromate PbCrO4 . PbO.

F Guigret's green is chemically hydrated chromium (III) oxide Cr2O

3.2H

2O

F Blister copper is 99% pure copper

F Scheelite is chemically calcium tungstate CaWO4.

F Tungsten blues have chemical composition WO2.67

(OH)0.33

and WO2.7

(OH)0.1

F Fulminating Gold is chemically NH = Au – NH2

F Action of heat on copper sulphate

CuSO4 . 5H

2O ⇔

Exposure CuSO4 . 3H

2O ⇔

373K CuSO4. H

2O ⇔

500K CuSO4

Bluish green White

F Chemical volcano. When crystals of red coloured ammonium dichromate are heated,a violent action takes place accompanied by flashes of light and nitrogen is liberatedleaving behind a dark green residue of chromium sesquioxide (Cr

2O

3).

(NH4)

2Cr

2O

7 N

2 + 4H

2O

+ Cr

2O

3

Ammonium dichromate Chromium sesquioxide



F The colours of some transition metal ions (aquated) are given below :Configuration Example Unpaired electrons Colour

3d0 Ti4+ 0 colourlessS c 3 + 0 colourless

3d1 T i 3+ 1 purpleV 4 + 1 b l u e

3d2 V 3 + 2 green3d3 Cr 3 + 3 violet

V2 + 3 violet3d4 Mn3 + 4 violet

Cr2 + 4 b l u e3d5 Mn2 + 5 p i n k

Fe3 + 5 yellow3d6 Fe2 + 4 green3d7 Co2 + 3 p i n k3d8 Ni2 + 2 green3d9 Cu2 + 1 b l u e3d10 Zn2 + 0 colourless

F Calculated and observed magnetic moment (BM) for transition metal ions are givenbelow:

Ion Configuration Unpaired Magnetic momentCalc. Obs.

S c 3 + 3d0 0 0 0T i 3+ 3d1 1 1.73 1.75T i 2+ 3d2 2 2.84 2.76V 2 + 3d3 3 3.87 3.86Cr 2 + 3d4 4 4.90 4.80M n + 3d5 5 5.92 5.96F e 2 + 3d6 4 4.90 5.3 – 5.5Co 2 + 3d7 3 3.87 4.4 – 5.2N i 2 + 3d8 2 2.84 2.9 – 3.4Cu 2 + 3d9 1 1.73 1.8 – 2.2Zn2+ 3d10 0 0



BORON FAMILY

F B2O

3 and B(OH)

3 are acidic, Al

2O

3 and Al(OH)

3 ; Ga

2O

3 and Ga (OH)

3 are amphoteric

while Ln2O

3 and Ln(OH)

3 are basic. Thus, on moving down the group, there is a

gradual change from acidic to amphoteric and then to basic character of the oxidesand hydroxides of the elements.

F The relative strength of trihalides of boron decreases in the order

BF3 < BCl

3 < BBr

3

F BCl3 exists as a monomer while aluminium chloride exists as a dimer Al

2Cl

6.

F Borazine or Borazole or inorganic benzene is B3N

3H

6.

F Structure of Boric acid. It is having a two dimensional sheet structure in whichdifferent triangular BO

33– units are bonded together by hydrogen bonds.

F Action of heat on orthoboric acid

(i) H3B O

3100ºC → HBO

2 + H

2O

Orthoboric acid Metaboric acid

(ii) 4HBO2

160ºC → H2B

4O

7 + H

2O

Metaboric acid Tetraboric acid

(iii) Above 160ºC, it swells up giving frothy mass and finally forms boron trioxide,B

2O

3.

F Ultramarines are complex silicates of aluminium and sodium with 12% sulphur. Blue ultramarinehas composition Na

5, Al

3 Si

2 S

3 O

12.

F The first three ionization energies of 13 group elements (in KJ mole–1) are given as under

B Al Ga In Tl

I 800.2 577.4 578.6 558.2 589.1

I I 2426.5 1816.1 1978.8 1820.2 1970.5

III 3658.7 2744.1 2962.3 2704.0 2877.4



F The atomic size of 13 group elements (in Pm) are given as under

B Al G a I n T l

90 143 135 167 170

F The melting points and boiling points of 13 group elements decrease on movingfrom top to bottom in the group.

B Al G a I n T l

Melting point (K) 2453 993.4 302.8 429.6 576.5

Boiling point (K) 3923 2740 2676 2353 1730

F The relative abundance of 13 group elements (in PPm) is given below :

B Al G a I n T l

9 83000 19 0.24 0.7

F The densities of 13 group elements increases from left to right in the periodic table.

B Al G a I n T l

Density (g/cm 3) 2.35 2.70 5.90 7.31 11.85

F The standard reduction electrode potentials of 13 group elements are given as under :

B Al Ga In Tl

– 1.87 V – 1.66 V – 0.56 V – 0.34 V + 1.26 V

F The enthalpies of fusion and vaporization of 13 group elements (in KJ mole–1) aregiven below :

B Al G a I n T l

∆ Hfusion

23.60 10.50 5.59 3.26 4.31

∆ Hvaporization

504.5 290.8 270.3 231.8 166.1

F B2O

3 is acidic in nature, Al

2O

3 and Ge

2O

3 are amphoteric while In

2O

3 and Tl

2O

3

are basic in nature.

F Trihalides of Al, Ga and In exist as dimers.

F Some important ores of Boron are given as under :

(i) Boric acid, H3BO

3

(ii) Borax, Na2B

4O

7.10H

2O

(iii) Boracite, 3Mg3B

3O

15.MgCl

2

(iv) Colemanite, Ca2B

4O

11.5H

2O

(v) Boranatrocalcite, Ca2B

4O

7.NaBO

2.8H

2O

(vi) Kernite or Razorite, Na2B

4O

7.4H

2O



F Some important minerals of aluminium are given as under :

(i) Corundum, Al2O

3

(ii) Diaspore, Al2O

3.H

2O

(iii) Bauxite, Al2O

3.2H

2O

(iv) Cryolite, Na3AlF

6

(v) Felspar, KAlSi3O

8

(vi) Alunite or Alum stone, K2SO

4.Al

2(SO

4)

3.4Al(OH)

3

(vii) Turquioise, AlPO4.Al(OH)

3.H

2O

(viii) Aluminates of Mg, Fe and Mn also occur in nature as spinels.

F Gallium is found distributed in most specimens of zinc blende. It also occurs in coalash and mineral germite.

F Indium occurs in all commercial samples of Tin and in the mineral cylindrite.

F Thallium occurs in many kinds of pyrites, in zinc ores and in the mineral crookesite.

F Boranes are boron hydrogen compounds with general molecular formula BnH

n + 4 or

Bn H

n + 6. They are electron deficient compounds. The lighter boranes (upto B

5)

spontaneously react with air where as remaining compounds are air stable. Thephysical properties of boranes are given as under :

Formula N a m e Melting point Boiling point

(ºC) (ºC)

B2H

6Diborane – 165.6 – 92.5

B4H

10Tetraborane – 120 18

B5H

9Pentaborane–9 – 46.6 48

B5H

11Pentaborane–11 – 123 63

B6H

10Hexaborane–10 – 62.5 110

B6H

12Hexaborane–12 – 82.3 80–90

B8H

12Octaborane–12 – 20 –

B8H

14Octaborabe–14 – –

B9H

15Enneborane 2.6 –

B10

H14

Decaborane 99.7 213

B20

H16

Isosaborane–16 196.2 –

F Melting and boiling points of halides of boron decrease in the order

BI3 > BBr

3 > BCl

3 > BF

3



F The halides of boron do not conduct electricity in the liquid state.

F Boric acid is a weak monobasic acid

B(OH)3 + 2H

2O ⇔ H

3O⊕ + [B(OH)

4]–1

PKa = 9.25

F It is difficult to titrate boric acid against NaOH solution and the end point cannotbe located correctly. However, it can be successfully titrated in the presence ofpolhydroxy alcohols (e.g., Glycerol, mannital, catechol or sugar). The presence ofthese compounds greatly increases the acidity of boric acid.

B(OH)3 + 2OH

OHH3O+ + B

O O

O O+ 2H2O

Boron is complexed by these compounds. These complex ions cannot interact withH + ions as boron atom has already acquired it's maximum covalency of four.Consequently, boric acid in presence of polyhydroxy alcohols can be titrated againstNaOH to a definite end point.

F Borax is a white crystalline solid which is sparingly soluble in cold water but isreadily soluble in hot water.

F Borax on heating, undergoes swelling due to the escape of water of crystallization assteam from it.

F Borax, which is normally written as Na2B

4O

7.10H

2O, contains tetranuclear units

[B4O

5(OH)

4]2– comprising BO

4 and BO

3 units. Thus, borax should have been

formulated as

Na2[B

4O

5(OH)

4] .5H

2O

F Aluminium trifluoride (AlF3) is different from other trihalides of Al in being insoluble

and nonvolatile. In AlF3, the coordination number of Al is six, in AlCl

3 t h e

coordination number of Al changes from 6 to 4 as it melts while in AlBr3 and AlI

3

the coordination number remains four. In AlF3 each Al is surronded by a distorted

octahedron of 6F atoms and 1 : 3 stoichiometry is achieved by the sharing of cornerfluorine atoms between two octahedra.

F Aluminium chloride (AlCl3) in the pure and anhydrous state is a white solid but commercial

samples are yellowish due to the impurity of FeCl3.



F Anhydrous AlCl3, in the crystalline state posesses a closely packed layer structure with six coordinated

alumnium having octahedral arrangement.

F Anhydrous AlCl3 has a very high affinity for water. On treating AlCl

3 with water the

Cl– ions go outside the coordination sphere to form [Al(H2O)

6] Cl

3 with enthalpy of

solution – 330 KJ mol –1. Due to this strong Al – O linkage the hydrate cannot bedehydrated on heating to form AlCl

3.

2[Al(H2O)

6]Cl

3 ∆ → Al

2O

3 + 6HCl + 9H

2O

F Aluminium chloride, is a polymeric solid which exists as a dimer Al2Cl

6 between

200–400ºC and then monomer upto 800ºC.

F Ammoniates are formed by the reaction of AlCl3 with NH

3

AlCl3 + 6NH

3 ———→ AlCl

3.6NH

3

F AlBr3 and AlI

3 form dimeric molecular compounds (Al

2Br

6 and Al

2I

6) in the solid as

well as liquid phases.

F Thermite welding . Aluminium has got a very high affinity for oxygen.

4Al + 3O2 ———→ 2Al

2O

3.

∆ H = – 3230 KJ mole–1

It, therefore, displaces metals less electropositive than itself from their oxides. Thelarge amount of heat produced is used in welding rails or heavy machinery withoutremoving them from their position. This is called thermite welding or Gold Schmidt'saluminothermic process. In this process, a mixture of Ferric oxide (3 parts) andaluminium powder (1 part) called thermite is used.

F Alloys of aluminium :

(i) Mangalium , contains 2 – 15% Mg alloyed with Al. It is used for making cheapbalances and machined articles.

(ii) Alclad. Duralumin, covered with a thin coating of aluminium is known as alclad.It is perfectly resistant to corrosion and is used for making sea planes.

(iii) Duralumin, contains 95% Al, 4% Cu, 0.5% Mn and 0.5% Mg. It is as light asaluminium, compared with mild steel in strength and toughness. It is used formaking air ships.

(iv) Y-alloy contains 92.5% Al, 2% Ni, 4% Cu and 1.5% Mg. It can be worked bothhot and cold and is used for making aeroplane parts.

(v) Aluminium bronze is an alloy of 10–12% Al with copper. It is used for making utensils,jewellery, decorative articles.

(vi) Precious gems. Alumina and aluminates form the basis of a number of precious gems whichoccur in nature. Some of them are given as under :



(i) Ruby, is carmine red in colour and contains traces of Cr.

(ii) Topaz , is chemically fluosilicates of aluminium and possesses straw yellow colour.

(iii) Jade, is chemically sodium aluminium silicate. It is found in number of coloursand shades e.g., white, green, red, orange, violet etc.

(iv) Fibrol i te , is chemically beryllium aluminium silicate and posesses a sapphireblue colour.

(v) Aquamarine is also chemically beryllium alumnium silicate but is bluish greenor greenish in colour.

(vi) Tourmaline is a complex borosilicate of aluminium and of traces of Na, K andMg. It has a straw yellow colour.

(vii) Phenacite is beryllium aluminate and is colourless like diamond.

(viii) Euclase is a natural variety of beryllium aluminate which is pale blue or bluishgreen in colour.

F Artificial gems are prepared as discussed here : An oxyhydrogen flame is directed ata small rod of alumina and finally divided mixture of alumina, fluorspar and a littlecolouring matter (e.g., Cr

2O

3 in case of Rubies) is allowed to fall into the flame. The

fused mass is caught by the rod of alumina where it is deposited in the form ofsingle pear shaped crystal which may be cut and polished. Artificial sapphires areproduced by mixing 5% titanium oxide and 1.5% Fe

2O

3 with alumina and heating

it on a reducing flame.

F Pseudo alums are double sulphates of a divalent and a trivalent metal which crystallizewith twenty four water molecules of crystallization, for example.

(i) MnSO4.Al

2(SO

4)

3.24H

2O

(ii) FeSO4.Al

2(SO

4)

3.24H

2O

They are not isomorphous with true alums.

F Lapislazuli is sodium aluminium sillicate with traces of Na2S. It is a rare mineral

and posesses beautiful blue colour.

F China clay is chemically Al2O

3.2SiO

2.2H

2O

F Alundum or Artificial corundum used as abrasive and refractory basic lining is produced byfusing bauxite at 3275 K in an arc furnace. The impurities are allowed to settle and the clear liquidis drained off. The resulting solid after cooling is crushed, mixed with clay and felspar, cast intomoulds and fired in kilns at 1775 K.

F Extraction of Aluminium. Al is usually extracted from Bauxite, Al2O

3.2H

2O. First, bauxite is

purified from the impurities (Red bauxite contains Fe2O

3 as impurity while white bauxite contains

silica as impurity). Red bauxite can be purified by Baeyer's process or Hall's process while whitebauxite is purified by Serpeck's process.



(a) Baeyer's process involves the roasting of the ore to convert FeO to Fe2O

3 and then digerted at

423 K with conc. NaOH solution for a few hours when Al2O

3 gets dissolved to give a solution of

[Al(OH)4]–1. The basic oxide impurities such as Fe

2O

3 are not effected.

Al2O

3 + 2OH–1 + 3H

2O ———→ 2Al(OH)

4–1

Aluminate ion

Fe2O

3 left undissolved is filtered off. The treatment of Al(OH)

4–1 solution with a

weak acid precipitates pure Al(OH)3.

Al(OH)4

–1 + H+ ———→ Al (OH)3 + H

2O

(White ppt.)

The Al(OH)3 precipitate is removed by filtration and ignited to get alumina, Al

2O

3.

(b) Hall 's process , Involves the fusion of the ore with Na2CO

3 when soluble sodium

meta aluminate, NaAlO2 is produced. This is extracted with water when Fe

2O

3 is

left as a residue.

Al2O

3 + Na

2CO

3 ———→ 2NaAlO

2 + CO

2

Sodium meta aluminate

The water extract is heated upto 333K and CO2 is passed through it. Al(OH)

3 is

precipitated due to hydrolysis and is ignted to get alumina, Al2O

3.

2NaAlO2 + 3H

2O + CO

2 ———→ 2Al(OH)

3 + Na

2CO

3

(c) Serpeck's process involves the heating of bauxite with coke in a current of N2 at

2075 K. The SiO2 present in the ore is reduced to silicon which volatilizes off and

alumina gives aluminium nitride. This can be hydrolysed to Al(OH)3 which on

fusion gives alumina.

SiO2 + 2C ———→ Si A + 2CO A

Al2O

3 + 3C + N

2 ———→ 2AlN + 3CO

Aluminium nitride

AlN + 3H2O ———→ Al (OH)

3 + NH

3.

Electrolysis of Al2O

3 to form aluminium : Pure alumina is dissolved in fused cryolite,

Na3AlF

6 at 1225 K by a current of 100 amperes and 6 – 7 volts to get Al. The Al

obtained is purified by Hoope's process.

F Boron nitride (BN), has a structure similar to that of graphite.

F Green edged flame test for borate (BO3

3–) ion. A mixture of C2H

5OH and BO

33– salt

with conc. H2SO

4 burns with green edged flame due to the formation of ethyl borate.

H3BO

3 + 3C

2H

5OH ———→ B(OC

2H

5)

3 + 3H

2O

Ethyl borate

F Boron carbide, B4C, is obtained by heating boron and carbon in an electric furnace.

4B + C ———→ B4C

It is one of the hardest substances known and is used as an abrasive.



F Charcoal cavity test for aluminium. On heating with Na2CO

3 and a drop of cobalt nitrate

solution a blue coloured residue of cobalt metaaluminate (Thenard's blue) is obtained.

2Al3+ + Co(NO3)

2 + O

2 ———→ Co(AlO

2)

2 + 2NO

2

blue residue

F NaOH solution gives a white gelatinous precipitate of Al(OH)3 with aluminium

salts. The precipitate dissolves in excess of NaOH due to the formation of sodiummetaaluminate.

Al3+ + 3OH –1 ———→ Al(OH)3

White ppt.

Al(OH)3 + OH – ———→ Al(OH)

4–1 or AlO

2– + 2H

2O

White ppt. Soluble

F Lake test for Al 3+ ion. To the Al 3+ ion solution in dilute HCl are added a few dropsof litmus and NH

4OH in excess. A blue gelatinous precipitate floating in colourless

solution is obtained.

F Mordants , are the chemical substances which help to fix a dye on a fabric. Most ofthe aluminium salts are good mordants for acidic dyes The fabric is dipped in salt ofa weak base, e.g., aluminium acetate, ferric alum and steamed when the metallichydroxide formed by hydrolysis is deposited in a finally divided state on the fabric.Now the fabric is dipped in a solution of the dye when it combines with the mordantto form a coloured adsorption compound known as lake which is permanentlyattached to the fabric.

F Zeolites have the general formula AlxSi

yO

2(x + y ) and for every 2Al 3+ replacing Si4+

two unipositive or one bipositive cation enters the lattce. The common natural zeoliteis nitrolith, Na

2Al

2Si

3O

10.2H

2O. The artificial zeolite is Na

2Al

2Si

3O

10.4H

2O. They

are used in water softening.

F Garnets are double silicates of a divalent metal [Ca, Mg or Fe(II)] and aluminium.They are beautifully coloured. Noble garnet has the composition (MgFe)

3Al

2Si

3O

12.

F Synthet ic lubricat ing oils involve the use of crude aluminium chloride for theirextraction in petroleum industry.

F Turquoise, Al2(OH)

3PO

4.H

2O and Wavellite (AlOH)

3(PO

4)

2.5H

2O are naturally occuring basic

phosphates of Al.

F Orthoborates are the compounds which contain discrete BO3

3– ions. For example, Ca3(BO

3)

2.



F Metaborates are the compounds in which each BO2 unit shares two oxyen atoms. The compounds

can have chain structure as in case of calcium metaborate Ca(BO2)

2 or ring structure.

F Pyroborates contain discrete B2O

54– ions i.e., in these ions the BO

3 units share one

oxygen atom.

F Complex borates contain 3 - as well as 4 - coordinated boron atoms. For example,borax Na

2B

4O

5(OH)

4. 8 H

2O.

F Carboranes are neutral molecules in which a BH– unit has been replaced byisoelectronic CH unit, e.g.,

B10

H4 + R

2S ———→ B

10H

12(R

2S)

2 + H

2

B10

H12

(R2S)

2 + R – C ≡ C – R' ———→ B

10H

10C

2RR' + 2R

2S + H

2

F Borazine (B3N

3H

6) is isoelectronic with Boroxine, H

3B

3O

3. It is prepared by the

explosive oxidation of B2H

6 or B

5H

9.

F Organometallic compounds of 13 group elements are given as under :

BF3 + 3C

2H

5MgI ———→ B(C

2H

5)

3.3Mg(I)F

AlF3 + 3C

2H

5MgI ———→ Al (C

2H

5)

3.3Mg(I) F

F Borax , exists in following forms :

(i) Prismatic borax. It is a decahydrate, Na2B

4O

7.10H

2O. This is obtained when a

borax solution is crystallized at ordinary temperature.

(ii) Octahedarl borax. It is a pentahydrate, Na2B

4O

7.5H

2O. It is obtained when a

borax solution is crystallized above 370 K.

(iii) Borax glass or anhydrous sodium tetraborate. It is obtained by heating ordinaryborax above it's melting point till whole of water of crystallization is lost as steam.

F Styx numbers are used to explain the nature of bonding in boranes.



CARBON FAMILY

F Catenation is the unique property of 14 group elements to form chains of identicalatoms. The tendency to show catenation decreases in the order

C > Si > Ge > Sn > Pb

F Inert pair effect the reluctance of ns electrons to take part in bond formation is calledinert pair effect. This effect is more pronounced in heavier elements and that too for13, 14 and 15 group. It results in the decrease in oxidation state by 2 units. Forexamples, Tl is more stable in oxidation state + 1 than the oxidation state + 3.

F In diamond, the carbon atom is sp3 hybridized and in graphite it is sp2. The C – Cbond distance in diamond is 154 Pm while in graphite it is 142 Pm. Diamond istetrahedral while graphite has hexagonal rings forming layers. The two layers in graph-ite are 336 Pm apart. Diamond is bad conductor while graphite is good conductor,diamond is hard while graphite is soft, density of diamond is 3.51 g/cc while that ofgraphite 2.25 g/cc at 298 K.

F The carbon content in different allotropes of carbon are given as under :

Allotrope Carbon content

Diamond 100%

Graphite 95 - 97%

Coal 60 - 90%

Charcoal 68 - 85%

Animal charcoal 8 - 10%

Lamp black 98 - 99%

F Some important alloys of tin are tabulated below :

Alloy Percentage composition Uses

Solder Sn 67% Pb 33% In soldering

Pewter Sn 75% Pb 25% In making utensils

Babit metal Sn 90% Sb 7% Cu 3% For making bearings

Britannia metal Sn 90% Sb 8% Cu 2% For making table wares

White metal Sn 82% Sb 12% Cu 6% For making table wares

Bell metal Sn 25% Cu 75% For making bells

Rose metal Sn 28% Pb22% Bi 50% For electric fuses

F Gold dissolves in aqua regia forming H[AuCl4] while Pt dissolves forming H

2 [PtCl

6]

F CO2 is a gas while SO

2 is a solid at room temperature.



F Trimethylamine (CH3)

3N is pyramidal while Trisilylamine N(SiH

3)

3 is planar due to

back bonding.

F SiCl4 is a Lewis acid but CCl

4 is not because carbon cannot expand it's octet due to

the absence of vacant d-orbitals.

F Freons are CFCl3, CF

2Cl

2, and CF

3Cl and they are used as refrigerants.

F Solid CO2 is also called dry ice or drikold.

F Inter calating compounds are formed by Graphite.

F Glass is an amorphous super cooled liquid with composition Na2O.CaO.6SiO

2.

F Carborundum is sillicon carbide SiC. It is used in high temperature semiconductors,fabrication of grinding wheels and in atomic reactors for making containers.

F White Lead is chemically Pb(OH)2. 2PbCO

3 and Red Lead is Pb

3O

4.

F Silicones are polymeric organosilicon compounds containing Si – O – Si linkages.They have high thermal stability of Si – O – Si chains and are also called hightemperature polymers.

General formula : (R2 SiO)

n. Where R = - CH

3, – C

2H

5, – C

6H

5

F Etching of glass HF reacts with glass to form hydrofluosilicic acid, H2SiF

6.

SiO2 + 4HF → SiF

4 + 2H

2O

SiF4 + 2HF → H

2 SiF

6

F Calcium boride is used as a deoxidizer.

F The two common forms of anhydrous Al2O

3 are α .Al

2O

3 called corrundum and

γ-Al2O

3 called activated alumina . The α -form is stable at high temperatures. It is

very hard and is resistant to hydration and to attack by acids. It is used as anabrasive. γ -Al

2O

3 is readily soluble in acids and is used in column chromatography.

F Boron and alumium form tetrahedral complexes like HBF4 and LiAlH

4. Ga, In and

Tl form ocahedral complexes.

F The atomic size of 14 group elements increases as

C < S i < G e < S n < P b

Atomic size (Pm) 77.2 117.6 122.3 140.5 146



F The melting points of 14 group elements (in K) are given as under :

C S i G e S n P b

4374 1693 1218 505 600

F The boiling points of 14 group elements (in K) are given as under :

C S i G e S n P b

– 3550 3123 2896 2024

F The densities of 14 group elements at 298 K (n g/cm 3) are given as under :

C S i G e S n P b

3.51 2.34 5.32 7.27 11.34

F The first four ionization energies of 14 group elements (in KJ mole –1) are given asunder :

C S i G e S n P b

I 1086 786 761 708 715

I I 2352 1573 1537 1411 1450

III 4619 3228 3301 2942 3081

I V 6221 4354 4409 3929 4082

F The electronegativities of 14 group elements are given as under :

C S i G e S n P b

2.5 1.8 1.8 1.8 1.9

F The electrical resistivities at 298 in ohm cm for 14 group elements are given asunder :

C S i G e S n P b

1014 – 1016 48 47 1.1 × 10–5 2 × 10–5

F Catenation is the unique tendency of 14 group elements to form long chains ofdifferent sizes and shapes. The tendency to show catenation is directly related to thestrength of bond. The bond energies of 14 group elements decrease as under :

C – C Si – Si Ge – Ge Sn – Sn Pb – Pb

Bone energy (KJ mole–1) 348 222 167 155 –

This is the reason why carbon forms many chains, Si, a few and Ge and Sn formpractically no chains.

F Formation of complexes by 14 group elements. The tendency of an element to formcomplexes is favoured by

(i) High charge



(ii) Small size of its atoms

(iii) The availability of orbitals of appropriate energy in it.

Carbon has no d-orbitals. So it does not form complexes while S, Ge, Sn and Pbform.

F Oxalic acid is much more stable than silico-oxalic acd (SiOOH)2.

F The hydrides of carbon, CH4, C

2H

6 etc., are very stable while those of silicon, e.g.,

SiH4 are eaisly decomposed by common reagents like alkalies, silver nitrate etc.

F Silicon is a bad conductor of electricity while some varieties of carbon are goodconductors.

F Allotropic forms of carbon. The allotropic forms of carbon are given as under :

(i) Diamond, a beautiful crystalline form

(ii) Graphite, a soft greyish black crystalline substance and

(iii) Amorphous carbon, black residue left when carbon compounds are heated.Different amorphous varieties of carbon are given as under :

(a) Coal

(b) Coke

(c) Charcoal or wood charcoal

(d) Bone black or animal charcoal

(e) Lamp black

(f) Carbon black

(g) Gas carbon

(h) Petroleum coke

F Diamonds are weighed in carats (1 carat = 200 mg)

F Koh-i-noor diamond was originally 186 carats while Pitt damond was 136.25 carats.

F Diamond crystal is a macromolecule. Each carbon atom is bonded tetrahedrally tofour other carbon atoms. The carbon carbon distance in diamond is 154 Pm.

F Diamond is the densest variety of carbon (density = 3.51 g/cm 3).

F Diamond is the hardest natural substance known and has a melting point of 4200 K.

F The refractive index of diamond is 2.45.



F The value of diamond depends upon it's size as well as colour. Bluish white diamondsare costlier than yellow ones. Black diamonds are not suitable as gems.

F Diamonds are insoluble in all solvents.

F Diamonds are bad conductors of heat and burn in air if heated to 1175 K formingCO

2 and leaving a trace of ash (about 0.05%) consisting of silica and iron oxide.

However, in vaccum, diamonds are stable upto 2075 K but at 2075 – 2275 K theyare converted into graphite.

F On heating with a mixture of K2Cr

2O

7 and conc. H

2SO

4 at 475 K, diamonds are

oxidized to CO2.

F Diamonds are acted upon by fused Na2CO

3.

F Uses of diamonds are given as under :

(i) Black diamonds are used for sawing marble, cutting glass, as a rock drills,phonographic needles and as an abrasive.

(ii) Diamond dies are used for drawing thin wires. Tungsten wires of diameter lessthan one sixth the diameter of human hair has been drawn by using diamond.

(iii) Due to their ability to reflect and refract light they are used as precious stones.

F Manufacture of graphite . Artificial graphite is prepared by Edward G. Acheson'sprocess by heating coke or anthracite coal with a little Fe

2O

3 or silica as catalyst in

a resistance type electric furnace.

F Black lead or Plumbago is another name for graphite.

F Graphite is a dark grey substance with characteristic greasy feel and metallic lusture.It crystallizes in hexagonal plates and varies in specific gravity from 2 to 3.

F Graphite , on heating with conc. HNO3 forms graphitic acid which is insoluble in

water and whose composition is not clear.

F Aqua dag is a suspension of graphite in water while oil dag is suspension of graphiteis oil. These are used as lubricants.

F Lamellar of Intercalat ion Compounds of graphite contain atoms or moleculesintroduced in the layers of graphite e.g., graphite reacts rapidly with molten K, Rband Cs or absorbs their vapours to form bronze or blue coloured compoundsdepending upon the number of layers invaded by the metal. One such compound is



C8K formed between graphite and potassium. This compound conducts electricity

because the graphite sheets remain flat and retain their π electron system. Theinvading species force the graphite. Species apart and their distance increases from335 Pm to 1000 Pm. These compounds are very reactive, self igniting in air andreact violently with water.

F Coal has the following varieties :

(i) Peat containing 60% carbon.

(ii) Lignite containing 70% carbon.

(iii) Bituminous containing 78% carbon.

(iv) Anthracite containing 83% carbon.

F The common variety of coal is bituminous.

F Coke. When coal is subjected to destructive distillation by heating in the absence of air, it losesseveral volatile constituents like coal gas, NH

3, benzene, phenol and tar and the residue is called

coke. It is a pure variety of carbon (80 to 95%).

F Wood charcoal is obtained when wood is heated strongly without access to air. It isused as a fuel, as a deodorant and decolourizing agent in the purification of water,decolourizing sugar solution, In gas masks and as a constituent of gunpowder.

F Bone black or animal charcoal is left as a residue when bones are subjected todestructive distillation. It consists of about 10% amorphous carbon deposited on aporous frame work of calcium phosphate derived from bones.

F Lamp black is obtained by burning tar and vegetable oils rich in carbon in insufficientsupply of air and depositing the root on wet blankets hung in a room. It is used inmaking Indian ink, printer's ink, black paint, varnishes and carbon paper.

F Carbon black is obtained by burning natural gas in a limited supply of air.

Carbon black is not so greasy as lamp black. It is added to the rubber mix used formaking automobile tyres.

F Gas carbon and petroleum coke. Gas carbon is the carbon scraped from the waals ofthe retort used for the destructive distillation of coal. Petroleum coke is depositedon the waals of the retort used for distillation of crude petroleum. Both are used inmaking electrodes.

F Sugar charcoal is obtained when sugar is heated strongly out of contact with air. Itis the purest form of carbon.



F Be and Al carbides react with water to produce CH4 while calcium carbide forms acetylene.

Be2C + 4H

2O ———→ CH

4 + Be(OH)

2

Al4C

3 + 12H

2O ———→ 4Al(OH)

3 + 3CH

4

CaC2 + 2H

2O ———→ Ca(OH)

2 + C

2H

2

F The uses of various forms of silica are given as under :

(i) Sand is used in making glass, as a building material in mortar and as abrasive.

(ii) Quartz is used as refractory, in optical instruments and for ultraviolet lamps.

(iii) Agate is used in preparing hard knife edges.

(iv) Rock crystal is used as a gem stone for lenses.

(v) Kiese lguhr is used as an absorbent, for example, for nitroglycerine in makingdynamite.

(vi) Silica gel is used as a dehydrating agent and as a medium for the dispersal offinely divided catalysts.

(vii) Fine amorphous silica is used as a filler for rubber goods.

F The three crystallne forms of silica are

(i) Quartz

(ii) Tridymite

(iii) Crystobalite

F Quartz (specfic gravty 2.66) is stable below 870ºC. The different varieties of quartzinclude rock crystal, gem stones such as amethysts and cairngorm. It crystallizes intrigonal system. Agate is a term applied to a mixture of various forms of silica.Trydymite (sp. gravity 2.26) is stable over the temperature range 870ºC–1470ºCand crystobalite (specfic gravity 2.32) is stable over the range 1470ºC – 1710ºC.They are metastable at the normal temperature and change slowly into quartz.

F The amorphous varieties of silica are chert, filnt, chalcedony, jaspar, etc.

F Carbon suboxide (C3O

2) is an evil smelling gas which can be prepared by the

dehydration of malonic acid with P4O

10.

C O O H

3CH2 → 3C

3O

2 + 4H

3PO

4

COOH + P4O

10Carbon

Malonic acid suboxide

On heating upto 200ºC, it decomposes into CO2 and carbon.

C3H

2 200ºC → CO

2 + 2C

The molecule is thought to have a linear structure.

O = C = C = C = O



F Role of water during setting of cement . During the setting of cement the processesinvolved are hydration and hydrolysis. Water is essential for gel formation. Sincehydration is an exothermic reaction cooling also results in proper setting of cement.

F Role of gypsum during setting of cement is to remove the fast setting tricalciumaluminate forming calcium sulphoaluminate.

3CaO.Al2O

3 + 3CaSO

4 + 2H

2O ———→ 3CaO.Al

2O

3.3CaSO

4.2H

2O

Consequently, the process of setting of cement gets retarded and this results inbetter strength of the mass which sets.

F Silanes are the hydrides of silicone. Their general formula is Sin H

2n + 2 where n has

maximum value of 6. SiH4 is called monosilane; Si

2H

6 is called disilane and so on.

F Silicon polymers or silicones are polymeric organosilicon compounds containing Si– O – Si linkages. Their general formula is (R

2SiO)

x. They may be linear, cyclic or

cross linked polymers.

F Silicones are used for making water proof cloth and paper.

F Vaseline , a grease is obtained from silicones.

F Sil icone rubber is used as window gasket insulation, sealants for buildings, spaceships and jet planes etc.

F Silicones provide excellent insulating material for electric motors and other electricappliances since they can withstand high temperatures without charing.

F Silicons are mixed in paints and enamels to make them resistant to the effects ofhigh temperatures, sunlight or chemicals.

F Ortho silicates contain discrete SiO4

4– tetrahedra e.g., Phenacite, (Be2SiO

4); willemite

(Zn2SiO

4); olivine (9 Mg

2SiO

4.Fe

2SiO

4); Zircon, (ZrSiO

4).

F Pyrosilicates are the simplest condensed silicates in which two SiO4

4– tetrahedra arejoined by one oxygen atom forming discrete Si

2O

76– ion e.g., thorteveitte, Sc

2(Si

2O

7)

3

and hemimorphite, Zn3( S i

2O

7).Zn(OH)

2.H

2O.

F Chain silicates are of two types.

(i) Having (SiO3

2–)n units

(ii) having (Si4O

116–)

n units



Examples :

( a ) Synthetic silicates are Li2SiO

3 and Na

2SiO

3

(b ) Pyroxene minerals like spodumene, LiAl(SiO3)

2; Jadeite, NaAl(SiO

3)

2; Enstatile

MgSiO3 and diopside CaMg(SiO

3)

2

F Cycl ic s i l i ca tes contains two oxygen shared per tetrahedra and the basic unit isS i

3O

96– e.g. , Benitoite, BaTiSi

3O

9, Catapleite, Na

2ZrSi

3O

9.2H

2O; Wollastonite,

Ca3Si

3O

9 and Beryl, Be

3Al

2Si

6O

18.

F Sheet silicates contain three oxygen atoms of each SiO4

4– tetrahedra shared togetherto form an infinte two dimensional sheet of the composition (Si

2O

52–)

n e.g., Talc,

Mg2(Si

2O

5)

2.Mg(OH)

2 and Kaolin, Al

2(OH)

4Si

2O

5.

F Three dimensional silicates are having SiO4

4– tetrahedron sharing all it's feur oxygenswith other SiO

44– tetrahedra. For example, quartz, tridymite and crystobalite.

F Feldspars is present in almost 67% igneous rocks. Feldspar ores are of the followingtypes;

(i) Orthoclase feldspars like Orthoclase, KAlSi3O

8; Celsian, BaAl

2Si

2O

8.

(ii) Plagioclase feldspars like Albite, NaAlSi3O

8; Anorthite, CaAl

2Si

2O

8.

F Zeolites are alumino silicates with general formula

Mx / n

[(AlO2)

x (SiO

2)

y].ZH

2O

Where M is metal ion like Na +, K+ or Ca 2+; n is the charge on the metal cation andz is the number of water molecules of hydration.

Some examples of zeolites are :

(i) Erionite, Na2K

2CaMg (AlO

2)

2 (SiO

2)

6.6H

2O

(ii) Gemelinite, Na2Ca (AlO

2)

2 (SiO

2)

4.6H

2O

(iii) Chabazite, Na2Ca(AlO

2)

2 (SiO

2)

4.6H

2O

The characteristic feature of zeolites is the open ness of the structure which permitsthe formation of channels and cavities of different sizes ranging from 200 – 1100Pm in diameter. Water molecules and a variety of other molecules lke NH

3, CO

2,

C2H

5OH etc. can be trapped in these cavities. Thus, zeolites act as ion exchangers

and molecular sieves.

F Ultramarines are the aluminosilicates which do not contan water and some extraanions such as Cl –, S

22– and SO

42– may also be present in the cavities. Most of the

ultramarines are coloured and find use as pigments. Some examples are :

(i) Sodalite, Na8(AlO

2)

6 (SiO

2)

6 Cl

2

(ii) Ultramarine, Na8 (AlO

2)

6 (SiO

2)

6.S

2

(iii) Nosean, Na8 (AlO

2)

6 (SiO

2)

6 SO

4



F Silica gardens. Water glass is chemically sodium silicate containing excess of silica. It's compositionvaries from Na

2SiO

3.SiO

2 to Na

2SiO

3.3SiO

2. Water glass is soluble in water and on placing the

crystals of different salts in water glass solution, beautiful growths are obtained which are calledsilica gardens.

F Silicic gel also called silica jelly is chemically, SiO2.xH

2O. It is obtaned by mixing

solutions of sodium silicate and ammonium chloride or sulphate.

F Silicic acid solution is produced when a dilute solution of sodium silicate s pouredslowly with stirring into an excess of dilute HCl. The mixture is dialysed in aparchment bag placed in distilled water when NaCl and HCl molecules diffuse outof the bag leaving a clear colloidal solution of silicic acid in the dialyser.

F Orthosilicic acid , (H4SiO

4) is obtained as a gelatinous white precipitate when SiF

4

s passed into water.

3SiF4 + 4H

2O ———→ 2H

2SiF

6 + H

4SiO

4 B

F Metasilicic acid , (H2SiO

3) is obtained by treating a concentrated solution of sodium

silicate with HCl.

Na2SiO

3 + 2HCl ———→ 2 NaCl + H

2SiO

3

F Mosaic gold (SnS2). Stannic sulphide exsts in yellow glistening scales which is used

for decorative purposes under the name mosaic gold. It is prepared by heating amixture of tin fillings, sulphur and NH

4Cl in a retort.

Sn + 4NH4Cl ———→ (NH

4)

2SnCl

4 + H

2 + 2NH

3

2(NH4)

2SnCl

4 + 2S ———→ SnS

2 + (NH

4)

2SnCl

6 + 2NH

4Cl

F Coal gas is obtained by the destructive distillation of coal. It contains 95% combustiblegases like H

2, CH

4, C

2H

4 and C

2H

2 and 5% noncombustible impurities like N

2 and

CO2. The approximate composition of coal gas is given as under :

Hydrogen 44 – 55%

Methane 25–35%

Carbon monoxide 4–11%

Nitrogen 2 - 12%

Ethylene, acetylene, benzene 2.5–5%

Carbon dioxide 0.3%

Oxygen 0–1.5%

F Water gas is a mixture of carbon monoxide and H2. It is obtained when a blast of

steam is forced up through white hot coke or coal.



C + H2O Steam → (CO + H

2)

Whi te Water gashot ∆ H = 1215 KJ mole–1.

F Carburetted water gas. The fuel value or the calorific value of water gas is increased by adding toit gaseous hydrocarbons obtaned by cracking of petroleum oils. The process is called carburetting.The approximate composition of carburetted water gas is given as under :

Hydrogen 30–40%

Saturated hydrocarbons 15–20%

Unsaturated hydrocarbons 10–15%

Carbon monoxide 20–28%

Carbon dioxide 0.2%

Nitrogen 2.5 – 5%

F Producer gas is essentially a mixture of carbon monoxide and nitrogen. It is obtained by burningcoke in a limited supply of oxygen.

F Semiwater gas is considered to be a mixture of water gas and producer gas. It's approximatecomposition is given as under

Hydrogen 10–12%

Carbonmonoxide 25–28%

Methane 1–1.5%

Carbon dioxide 4–5%

Nitrogen 50–55%

F Oil gas is the gaseous fuel commonly used in laboratories. It is obtained by the cracking of keroseneoil in an oil gas plant .e.g.,

C16

H34

———→ 6CH4 + 2C

2H

4 + C

2H

2 + 4C

Hexane

F Natural gas. Putrefaction of vegetable matter under water yields marsh gas or methane. This isthe principal constituent of natural gas which issues from wells mainly situated in the oil producingregions. It is an excellent low cost fuel.

F Dry ice is another name for solid carbon dioxide :

In the laboratory, it is prepared by tying a canvas bag round the nozal of a carbondioxide gascylinder and releasing the pressure. Flakes of solid CO

2 collect in the bag and can be collected. It is

a soft white solid with density 1.53 g/cm3 and melting point 216.4 K at 5.2 atm. It producessevere blisters if pressed with hand and causes burns on hand. Dry ice when mixed with alcohol,ether or acetone produces intense cooling and is used as freezing mixtures.



F Some of the important uses of dry ice are given as under :

(i) Artificial rain s caused by spraying small pellets of dry ice over clouds with thehelp of aeroplanes.

(ii) For surgical operations of sores in hospitals.

(iii) As a refrigerant under the name drikold in cold drinks and for the manufactureof ice cream.

(iv) In the transport of perishable food stuffs.

F Permonocarbonic ac id is chemically HO.O.COOH and perdicarbonic acid ischemically HOOC – O – O – COOH.

F Carbonyl chloride, Phosgene (COCl2) is a colourless gas. It is easily decomposed by

water to CO2 and HCl.

COCl2 + H

2O ———→ CO

2 + 2HCl

Phosgene reacts with NH3 to form urea (carbamide)

COCl2 + 4NH

3 ———→ H

2N.CO.NH

2 + 2NH

4Cl

Urea

It is used in warfare.

F Carbon disulphide (CS2) is formed by passing sulphur vapours over red hot char-

coal.

C + 2S CS2

∆H = 79.4 KJ mole –1.

CS2 finds extensive use in the following processes :

( i ) As an excellent solvent for rubber, phosphorus, waxes, resins, oils, fats,sulphur etc.

(ii) In the extraction of oils from oil seeds.

(iii) In the vulcanization of rubber.

(iv) In the manufacture of carbon tetrachloride.

( v ) For killing rats and mice.

(vi) As an insecticide for curing the insect effected seeds and for killing rats.

(vii) As a solvent in the manufacture of varnishes.

F Carbon monoxide (CO) is a colourless toxic gas. It's toxic nature is attributed to it'sability to bind with iron in hemoglobin of blood to form carboxy haemoglobinwhich cannot take up oxygen of the air causing suffocation and finally death.

F Tin exists in three allotropic forms : grey, white and rhombic.

Grey 18ºC White 161ºC Rhombic

Density, 5.74 g/cm3 Density, 7.32 g/cm3 Density, 6.55 g/cm3



F Tin Pest or tin disease. The conversion of white tin into grey tin takes place very slowly at 18ºCwhich is it's transition temperature. However, if the temperature is as low as –50ºC and a smallamount of grey tin is already present, the conversion becomes rapid. This conversion is called tinpest or tin - disease.

F Tin Cry. Tin metal when bent produces a cracking noise due to rubbing of metalcrystals over one another.

F Action of conc. HNO3 on tin

( a ) Dilute HNO3

4Sn + 10HNO3 4 Sn (NO

3)

2 + NH

4NO

3 + 3H

2O

.

(b ) Hot conc. HNO3

Sn + 4HNO3 H

2SnO

3 + 4NO

2 + H

2O

Metastannic

acid

F Action of alkalies on tin. On heating with conc. alkali solution, tin evolves H2 gas.

Sn + 2NaOH + H2O

Na

2SnO

3 + 2H

2

Sodium stannate

F Some Important alloys of tin are given as under :

Name of alloy Percentage composition UsesSolder Sn 67%, Pb 33% In soldering

Pewter Sn 75%, Pb 25% In making cups, mugs and other utensils

Babbit metal Sn 90%, Sb 7%, Cu 3% In making bearings for machinery

Britannia metal Sn 90%, Sb 8%, Cu 2% For making table wares.

White metal Sn 82%, Sb 12%, Cu 6% For making gongs etc.

Bell metal Sn 25%, Cu 75% For making bells, gongs etc.

Rose metal Sn 28%, Pb 22%, Bi 59% For making electric fuses.

F Type metal is an alloy containing 82% Pb, 15% Sb and 3% Sn. It is used for makingprinting type.

F Lipowitz alloy contains Bi 50%, Lead 27%, Sn 13% and Cd 10%.

F Newton's metal contains Bi 50%, Pb 31% and Sn 19%.

F Plumbo solvency. Lead dissolves in water containing dissolved air, due to the formation of leadhydroxide. This solvent action of water on lead is called Plumbo solvency.

F Massicot is a yellow powder and is chemically, lead monoxide, PbO, It is used in making glass; inpaint and varnishes; in making lead salt and glazing pottery.



F Red lead is a red powder insoluble in water and is chemically Pb3O

4. It is used in making protective

paint for iron and steel and match industries; as an oxidizing in the laboratory.

F Red lead (Pb3O

4) is considered to be mixture of lead monoxide and lead dioxide and

it is written as (PbO2.2PbO).

F Lead dioxide or peroxide of lead (PbO2). It is a brown powder obtained by the

treatment of red lead with HNO3.

Pb3O

4 + 4NHO

3 2Pb (NO

3)

2 + PbO

2 + H

2

It is used as an active material of the positive plate in storage cells and finds use inmatch industry as an oxidizing agent.

F Lead sesquioxide (Pb2O

3) is obtained by heating lead monoxide to 775 K in air

4PbO + O2 2Pb

2O

3.

It is similar in behaviour to red lead.

F Lead carbonate and white lead. It occurs in the native state as cerrusite. In thelaboratory, it may be obtained by adding NaHCO

3 solution to the solution of a lead

salt

Pb(NO3)

2 + 2NaHCO

3 2PbCO

3 ↓ + 2NaNO

3 + CO

2 + H

2O

If instead of adding NaHCO3 solution, we add Na

2CO

3 solution to the lead salt, the

basic lead carbonate 2PbCO3 . Pb(OH)

2 is precipitated. It is extensively used in

paints.

F Sugar of lead is chemically lead acetate, (CH3COO)

2 Pb. It is prepared by dissolv-

ing lead oxide or lead carbonate in acetic acid and crystallizing the solution.

PbO + 2CH3COOH (CH

3COO)

2Pb + H

2O

PbCO3 + 2CH

3COOH (CH

3COO)

2Pb + H

2O + CO

2

Sugar of lead is used for making white lead, in medicine as lead lotion, as a mordantin dyeing and calico printing, in the manufacture of lead pigments and treating ivypoisoning.

F Lead chromate (PbCrO4) is prepared by mixing lead acetate and potassium chromate solution.

Pb(CH3COO)

2 + K

2CrO

4 PbCrO

4 ↓ + 2CH

3COOH

It finds use as a yellow pigment under the name chrome yellow or orange yellow.

F Chrome red, basic lead chromate Pb (OH)2 . PbCrO

4 is a red pigment and is obtained by

boilling chrome yellow with an alkali solution.



F Lead accumulator is a type of reversible cell which can be recharged. It works on the principle thatelectric energy can be converted into potential chemical energy and vice versa.

F Paints and Pigments. A paint may be defined as a fluid of finally divided solidwhich when applied to a surface will dry upto an opaque or transparent film eitherby oxidation or evaporation. A paint is made up of two parts :

( i ) A solid which when dispersed in a medium gives a paint. This is called apigment.

(ii) A liquid known as the vehicle, in which the pigment is dissolved to yield apaint.

F White p igments include basic lead carbonate (white lead), titanium dioxide,Lithopone, basic lead sulphate, and zirconium oxide.

F Red pigments include iron oxide, red lead, alizarin and cadmium red.

F Black pigments include carbon black, lamp black and bone black.

F Orange and yellow pigments include chrome yellow, zinc chromate, molybdenumorange, organic pigments and dyes.

F Green pigments include chromium oxide and Paris green.

F Blue pigments include ultramarine blue.

F The main ores of lead are

(i) Glena, PbS

(ii) Cerrusite, PbCO3

(iii) Anglesite, PbSO4

F Occurrence of Germanium. It is mainly obtained from flue dust, coal ash or the mineral germanitewhich contains about 6% Germanium.

F Germainum has a diamond type lattice.

F Germainium has melting point 1218 K which is intermediate between the very highvalues of non metallic carbon and silicon and the low value of distinctly metallic tin and lead.

F Germanes are the compounds formed by germanium with hydrogen. Some examples are, GeH4,

Ge2H

6, Ge

3H

8 and Ge

4H

10.



F The principal ore of tin is tinstone which contains only 10% of the metal as SnO2, the rest being

siliceous matter, tungstates of iron and manganese and pyrites of iron, copper and arsenic.

F Some important uses of tin are :

( i ) For tin plating sheets of iron and steam.

(ii) In tinning household utensils.

(iii) As tinfoil for wrapping cigarretes.

(iv) In the manufacture of alloys.

( v ) For the preparation of tin compounds commonly used as mordants in dyeingand calico printing. In the form of tin amalgam, it is used for making mirrors.

F Tinning is the process of covering the utensils with a thin layer to tin, a metal noteffected by the atmosphere or organic acids.

α-stannic acid is obtained as a white gelatinous precipitate by the action of NH3 on

the solution of stannic salts e.g., stannic chloride, SnCl4.

SnCl4 + 4NH

4OH 4NH

4Cl + Sn(OH)

4

Sn (OH)4 SnO (OH)

2 + H

2O

α- stannic acid

β-stannic acid is obtained when α -stannic acid is allowed to stand. This form is notso readlly soluble in alkalies and is practically insoluble in acids. It's composition isH

2Sn

5O

11.4H

2O. Utensils are cleaned thoroughly by rubbing with sand and heated,

On sprinkling some NH4Cl on the hot surface, HCl is liberated.

NH4Cl NH

3 + HCl

The HCl formed removes any oxide layer present on the surface. A little tin isrubbed on the hot surface and uniformly distributed all over the surface with thehelp of a rag dipped in NH

4Cl powder.

F Stannic acids are of two types : (a) α-stannic aicd (b) β -stannic acid

F Stannous chloride, SnCl2.2H

2O

can be prepared by dissolving tin in HCl and con-

centrating the solution.

F SnCl2.2H

2O, on heating undergoes hydrolysis to form it's basic chloride Sn(OH).Cl.

The anhydrous salt, cannot, therefore, be obtained by heating the hydrated salt.

F Stannous chloride reduces mercuric chloride (HgCl2) to a white precipitate of mer-

curous chloride (Hg2Cl

2) which finally turns to metallic mercury (dark grey or black)

2Hg 2+ + 3Cl– + Sn2+ Hg2Cl

2 + Sn4+

Mercuric ion Mercurous chloride

Hg2Cl

2 + SnCl

2 2Hg ↓ + SnCl

4

Black



F Stannic Chloride, SnCl4 is a colourless fuming liquid (b. point 387.1 K), having sharp unpleasent

odour. It catches fire with turpentine oil. It combines with small quantities of water forming solubleand crystalline hydrates like SnCl

4.3H

2O; SnCl

4.5H

2O; SnCl

4.6H

2O and SnCl

4.8H

2O. How-

ever, with excess of water is forms stannic acid

SnCl4 + H

2O Sn(OH)Cl

3 + HCl

Sn(OH)Cl3 + 3H

2O Sn(OH)

4 + 3HCl

F Butter of tin SnCl2.5H

2O is used as a mordant.

F Pink salt is ammonium chlorostannate

F Analytical detection of stannous (Sn2+) ion

( a ) With H2S, a black ppt. of stannous sulphite, SnS is obtained.

(b ) With mercuric chloride (HgCl2) solution, a white ppt. of mercurous chloride

(Hg2Cl

2) is formed which turns grey on warming.

SnCl2 + 2HgCl

2 SnCl

4 + Hg

2Cl

2

White ppt.

SnCl2 + Hg

2Cl

2 SnCl

4 + 2Hg

Black

(c) With NaOH solution, a white ppt. of stannous hydroxide is obtained which issoluble in excess of NaOH solution forming sodium stannite, Na

2SnO

2.

SnCl2 NaOH → Sn(OH)

2 NaOH → Na

2SnO

2

White ppt. Soluble

F Analytical detection of stannic (Sn4+) ion

(i) With H2S, a yellow ppt. of stannic sulphide is obtained.

(ii) With NaOH solution, a white ppt. of stannic hydroxide is obtained which issoluble in excess forming sodium stannate, Na

2SnO

3.

SnCl4 NaOH → Sn(OH)

4 NaOH → Na

2SnO

3

White ppt. Soluble



NITROGEN FAMILY

F The bond angle in the hydrides of 15 group elements decreases as

NH3 > PH

3 > AsH

3 > SbH

3

F Thermal stability of hydrides of 15 group decreases in the order

NH3

> PH3 > AsH

3 > SbH

3 > BiH

3

F Hydrazoic acid N3H is a weak acid and it's strength is almost equal to that of acetic

acid.

F Thomas slag also known as phosphatic slag is a biproduct of steel industry. It contains14 - 18% P

2O

5 and 40% of lime which can be useful in lowering soil acidity.

F Chlorine reacts with NH3 as follows :

(a) If NH3 is in excess, Cl

2 oxidizes NH

3 to N

2.

8NH3 + 3Cl

2 → 6NH

4Cl + N

2

(b) If Cl2 is in excess, an explosive NCl

3 is formed.

NH3 + 3Cl

2 → NCl

3 + 3HCl

F HNO3 oxidizes sucrose to oxalic acid

C12

H22

O11

+ 18 [O] → 6 (COOH)2 + 5H

2O

from HNO3

Oxalic acid

F HNO3 is yellow in colour due to the dissolution of NO

2 gas formed during the

decomposition of some HNO3.

4HNO3 → 4NO

2 + 2H

2O + O

2

The yellow colour of the acid is removed by passing CO2 gas through it when NO

2

gets removed.

F Some oxy acids of phosphorous are

Acid Chemical formula Oxidation state of P

Hypo phosphorous acid H3PO

2I

Ortho phosphorous acid H3PO

3I I I

Hypo phosphoric acid H4PO

6I V

Ortho phosphoric acid H3PO

4V

Pyro phosphoric acid H4P

2O

7V

Meta phosphoric acid H P O3

V



F Holme's signals. A mixture of Ca3P

2 and CaC

2 on treatment with H

2O forms PH

3

and P2H

4 along with C

2H

2. The mixture burns with a bright luminous flame and it

acts as a signal for approaching ships.

Ca3P

2 + 6H

2O → 3Ca(OH)

2 + 2PH

3

CaC2 + H

2O → Ca(OH)

2 + C

2H

2

F The atomic radii of 15 group elements (in Pm) are given as under :

N P A s S b B i

70 110 120 140 150

F The melting point of 15 group elements (in K) are given as under :

N P A s S b B i

63 317 1089 903.7 544.4

F The boiling points of 15 group elements (in K) are given as under :

N P A s S b B i

77.2 553.5 888 1860 1837

F At 293K, the densities of 15 group elements (in g/cm 3) are given as under :

N P A s S b B i

0.879 1.823 5.778 6.697 9.808

F The electronegativity values of 15 group elements are given as under :

N P A s S b B i

3.0 2.1 2.0 1.9 1.9

F The abundance of 15 group elements in earth's crust (in PPm) is given as under :

N P A s S b B i

19 1120 1.8 0.2 0.008

F The first three ionization energies of 15 group elements (in KJ mole –1) are given asunder :

N P A s S b B i

I . 1402 1012 947 834 703

II. 2856 1903 1798 1595 1610

III. 4577 2910 2736 2443 2466

F Occurrence of 15 group elements. Only P does not occur free in nature. Nitrogenforms 78% by mass and 80% by volume of the atmosphere. As, Sb and Bi occur freein nature. P is the eleventh most abundant element on earth's crust.



F Stabil ity of the hydrides of 15 group elements decreases from NH3 to BiH

3. The

decombosition temperatures of these hydrides (in K) are given as under :

NH3

PH3

AsH3

SbH3

BiH3

1573 673 553 423 very unstable

F The strengths and solubilities of oxyacids of 15 group elements are given as under.

HNO3

H3PO

4H

3AsO

4H

3SbO

4H

3BiO

3

Strong W e a k Weaker Amphoteric Bas ic

(Soluble) (Soluble) (Soluble) (Insoluble) (Insoluble)

F N and P are nonconductors, As is a poor conductor, Sb is a good conductor and Biis an excellent conductor.

F Acidity of oxides and the solubility of 15 group oxides decreases from N to Bi. Forexample, N

2O

3, N

2O

5, P

4O

6, P

4O

10, As

4O

6 and As

4O

10 are acidic and dissolve in

water forming acids. Sb4O

6 and Sb

4O

10 are weakly acidic and insoluble in water

while Bi2O

3 is a basic oxide and is insoluble in water.

F Physical states of 15 group elements are given as under :

Nitrogen is a gas; phosphorus is a soft, waxy and lustureless solid, Arsenic is hardlustureless solid while Sb and Bi are hard solids with metallic lusture.

F Allotropic forms of phosphorus are

(i) White phosphorus

(ii) Red phosphorus

(iii) Black phosphorus

(iv) White phosphorus is most reactive while black phosphorus is least reactive.

F White phosphorus, due to more reactivity it is stored under water to protect it fromair while red and black phosphorus are stable in air.

F The oxides of nitrogen are given as under :

Formula N a m e Oxidation state of Nitrogen

N2O Nitrous oxide + 1

N O Nitrogen monoxide + 2

N2O

3Dinitrogen trioxide + 3

NO2

Nitrogen dioxide + 4

N2O

4Dinitrogen tetraoxide + 4

N2O

5Dinitrogen pentaoxide + 5



F Nitrous ox ide (N2O) has a linear structure and is considered to be a resonance

hybrid of the following structures :

–: N = N = O : ↔ : N ≡ N – O :

: : ::

+ + –

F Nitric oxide (NO) has the following structure :

This is explained in terms of Pauling's special hypothesis of a three electron bondwhich is half as strong as a two electron bond. Due to the presence of odd electron,gaseous nitric oxide is paramagnetic in nature. Nitric oxide, is a resonance hybrid ofthe following two structures :

Nooo oo Ooo

oo oo ← → Noooo oo–

O+oo

ooo

F Dinitrogentrioxide (N2O

3) is assumed to have the following planar structure :

F Nitrogen dioxide (NO2) is an angular molecule with O - N - O angle 134º. An

unshared electron resides on nitrogen which is responsible for it's tendency todimerise. Due to the presence of odd electron, it is paramagnetic in nature.

F Dinitrogen tetraoxide (N2O

4) exists in a planer structure.

F The oxoacids of nitrogen are given as under :

Formula N a m e Oxidation state Comments about

of nitrogen acidic nature

H2N

2O

2Hyponitrous acid + 1 Weak acid

H4N

2O

4Nitroxylic acid + 2 Explosive

HNO2

Nitrous acid + 3 Unstable, weak acid

HNO3

Nitric acid + 5 Stable, strong acid

HNO4

Peroxynitric acid + 5 Unstable, explosive



F Hyponitrous acid (H2N

2O

2) has the anion N

2O

22– which has the following structure:

ON = N

O2 −

F Nitrous acid (HNO2) has the anion NO

2–1 which has the following structure :

O O

N132º

113 Pm

It may be assumed to be made up of the following resonating structures :

–O O

N ↔ –O O

N

F Nitric acid (HNO3) in the gaseous state has a planar structure.

130º N O141 Pm

116º 102ºH

96 Pm

O

O114º

122 Pm

F Peroxynitric acid (HNO4) is an unstable and explosive compound whose smell re-

sembles bleaching powder. It's structure is given as under :

HO – O – N = O

↓O

F The oxoacids of phosphorus are given as under :

Formula Name of acid Oxidation state Comments about

of phosphorus acidic nature

H3PO

2Hypophosphorus acid + 1 Weak, monobasic,

strong reducing agent

H3PO

3Phosphorus acid + 3 Dibasic acid,

strong reducing agent

H4P

2O

6Hypophosphorus acid + 4 Tetrabasic

H3PO

4Orthophosphoric acid + 5 Tribasic

H4P

2O

7Pyrophosphoric acid + 5 Tetrabasic

H P O3

Metaphosphoric acid + 5 Monobasic



F Hypophosphorus acid (H3PO

3) has the following structure :

H

O P OH

H

|–

|=

F Phosphorus acid (H3PO


H|P

OHOHO

F Hypophosphoric acid (H4P

2O


OH OH

O P P O

OH OH

| |

| |= −−−−−−−− =

F Orthophosphoric acid (H3PO

4) has the following tetrahedral structure :

O||P|OH

OHHO

F NCl3 is hydrolysed with H

2O to NH

3 and HOCl.

NCl3 + 3H

2O NH

3 + 3HOCl

F PCl3 is hydrolysed with water to form phosphorus acid, H

3PO

3.

PCl3 + 3H

2O H

3PO

3 + 3HCl

F PCl5 on hydrolysis forms phosphoric acid, H

3PO

4.

PCl5 + 4H

2O H

3PO

4 + 5HCl

F Nitrogen is a gas while other elements of 15 group are solids and have allotropicforms.



F Nitrogen is diatomic and exists as N2 while other 15 group elements are tetraatomic

e.g. , P4, As

4, Sb

4.

F The oxides of nitrogen are monomeric while the trioxides and pentaoxides of other15 group elements are dimeric.

F Nitrogen cannot form complexes by accepting long pair of electrons due to theabsence of d-orbitals while the other elements of 15 group form complexes.

F Nitrogen forms more number of oxides than other 15 group elements.

F Nitrogen hydride (NH3) forms an associated and high boiling liquid due to hydro-

gen bonding which is not the case with other 15 group hydrides.

F Linde's process is used for the industrial preparation of N2 by the fractional evapo-

ration of liquid air.

F Joule Thomson's effect. When a gas under pressure is allowed to expand suddenlythrough a small orifice into a region of low pressure, it is accompanied by cooling.

F Nitrogen is a colourless, odourless and tasteless gas. It is slightly soluble in water. Itis not poisonous but animals die in an atmosphere of nitrogen for want of oxygen.

F Fixation of nitrogen. The conversion of free atmospheric nitrogen to a nitrogencompound is called fixation of nitrogen. The different methods involved during thenitrogen fixation are :

( i ) Manufacture of nitric acid (Birkland - Eyde process).

(ii) Manufacture of ammonia (Haber's process)

(iii) Manufacture of calcium-cyanamide.

(iv) Preparation of nitrides.

( v ) Nitrogen fixation in nature.

F Calcium cyanamide (CaCN2) on heating with superheated steam at 450 K forms

NH3.

CaCN2 + 3H

2O CaCO

3 + 2NH

3

Calcium cyanamide

F Serpeck's process for the purification of white bauxite evolves NH3 as the biproduct.

Bauxite is mixed with coke and heated in a current of nitrogen when AIN is formedwhich is hydrolysed with water to give NH

3.



Al2O

3 + 3C + N

2 2AIN + 3CO ↑

AIN + 3H2O AI(OH)

3 + NH

3

F The latent heat of vaporization of NH3 is 1380 J. It is, therefore, extensively used in

ice plants for refrigeration.

F Action of chlorine on NH3.

( a ) With excess of NH3

2NH3 + 3Cl

2 N

2 + 6HCl

6NH3 + 6HCl 6NH

4Cl

______________________________________

8NH3 + 3Cl

2 N

2 + 6NH

4Cl

(b ) With excess of Cl2

NH3 + 2Cl

2 NCl

3 + 3HCl

F Ammonium reacts with chloroplatinic acid, H2PtCl

6 to give a yellow precipitate of

ammonium chloroplatinate.

2NH3 + H

2PtCl

6 (NH

4)

2PtCl

6

Yellow ppt.

F Ammonium compounds give a white ppt. of ammonium acid tartarate with a satu-rated solution of sodium hydrogen tartarate.

NH4Cl + NaCH

4H

4O

6 NH

4HC

4H

4O

6 ↓ + NaCl

Sodium White ppt.Hydrogen tartarate

F Paranitrobenzene diazonium chloride gives a red coloration with traces of ammo-nium compounds.

F With Nessler's reagent, K2HgI

4, ammonium salts give a reddish brown ppt. of Million's

base (H2N.HgO.Hgl).

F Raschig method for the preparation of hydrazine involves the treatment of a strongaqueous solution of NH

3 with sodium hypochlorite (NaOCl) in presence of a little

glue.

NH3 + OCl– NH

2Cl + OH –

NH3 + NH

2Cl H

2N – NH

2 + HCl

Hydrazine



F Basic nature of hydrazine

H –––– N –––– N

H H

H

It is a weak diacid base. It can form salts with one or two equivalents of an acid.Hydrazine is less basic than ammonia. Hydrazine molecule has an unsymmetricalstructure in which the NH

2 groups do not rotate freely. This is due to the tendency

of the unshared electron pairs to get as far apart as possible.

In respect of structure, hydrazine resembles hydrogen peroxide and is the aminoanalogue of the latter.

OH – OHNH3 → H

2N – NH

2

Hydrogen peroxide Hydrazine

F Hydrazoic acid (N3H) is a colourless volatile liquid with a highly obnoxious odour.

It is poisonous in nature. It explodes violently when heated or struck. It is readilysoluble in water and alcohol. It boils at 310 K and when solidified melts at 186 K.

F Hydrazoic acid has the following resonating structures :

H – N = N = N+ –

↔ H – N = N ≡ N+–

F Nitric acid is used

(i) In the manufacture of explos ives l ike T.N.T. , p icr ic ac id and smokelesspowder.

(ii) In the manufacture of fertilizers.

(iii) In the manufacture of perfumes, dyes and medicines from coal tar products.

(iv) In the preparation of artificial silk.

(v) In the purification of gold and silver.

(vi) In the manufacture of H2SO

4.

F Phosphorus occurs in combination only as phosphates. For example, Phosphorite,

Ca3(PO

4)

2; Chlorapatite, 3Ca

3(PO

4)

2.CaCl

2; Fluorapatite, 3Ca

3(PO

4)

2.CaF

2.

F Labourers working with white phosphorus suffer from a disease in which the jawbones decay (Phossy jaw).

F Phosphorescence is the glowing of white phosphorus in the dark.

F White phosphorus when heated in the absence of air at 420 K is converted into redphosphorus.



F Some main points of difference between white phosphorus and red phosphorus aregiven as under :

Property White Phosphorus Red Phosphorus

(i) Physical state Pale yellow soft solid, Dark and brittleCan be cut with knife. powderWhite when freshly cut.

(ii) Odour Garlic Odourless

(iii) Density 1.8 g/cm 3 2.1 g/cm 3

(iv) Solubility Soluble in CS2

Insoluble

(v) Ignition temperature 303 K (melts under 533 (does not meltwater at 317 K) but sublimes)

No action

(vi) With hot caustic soda Dissolves and PH3

No actionis evolved

(vii) Physiological action Poisonous Non-poisonous

(viii) With chlorine Combines readily Combines onlyforming PCl

3, PCl

5on heating.

F Lucifer matches or strike-anywhere matches or frication matches are prepared asunder :

( i ) The match sticks are first dipped in a combustible material like moltensulphur or paraffin to about one cm length.

(ii) At the extreme tip match sticks are dipped in a paste containing the followingconstituents :

( a ) A readily combustible substance like antimony trisulphide,Sb2S

3.

( b ) A low kindling material which starts combustion. For example, redphosphorus or phosphorus trisulphide.

(c) An oxidizing agent like KClO3, KNO

3 or red lead which supplies oxygen

needed for combustion.

(d) An inert substance to cause friction and decrease sensitiveness. Forexample, glass powder or chalk.

(e) A binding material like glue which binds the various constituentstogether and enables them to stick to the match head.

(iii) This is next dipped in molten wax to provide a thin protective coating to thetip of the match stick.

To prevent after glow, the match sticks are Impregnated with borax. These matchsticks are extinguished immediately after they are blown without glowing for anyappreciable time.

When the match head is rubbed against any rough surface, low kindling materiall ike P

4S

3 catches fire due to heat produced by frication. The easily combustible

substance like Sb2S

3 is lighted followed by sulphur and finally by the match stick.

The oxidizing agents supply necessary oxygen for combustion.



F Safety matches differ from strike anywhere matches in the manner that the lowkindling material like phosphorus is absent from the tip. This is present in thecomposition pasted on side of the box. The paste applied to the side of the box isobtained by mixing Red P or P

2S

3 with sand or glass powder and glue.

When a safety match is rubbed against the special surface, a trace of P is detachedand ignited locally by heat due to friction. This tiny spark lgnites Sb

2S

3 and sulphur

and match stick is lightened.

F Smoke screens involve the use of calcium phosphide, Ca3P

2. The PH

3 gas obtained

from Ca3P

2 catches fire to give the needed smoke.

F Holme's signals. A mixture CaC2 and Ca

3P

2 is taken in a container which is pierced

and thrown into the sea. PH3 liberated catches fire and lights up acetylene. The

burning gases serve as signals to the approaching ships.

F Requisite qualities of a fertilizer

(i) It must provide the necessary constituents required for the plant growth.

(ii) Slightly basic soil (pH 7 to 8) is a must for the proper growth of plants. A goodfertilizer is, therefore, the one which is basic.

(iii) It must be soluble in soil moisture and get assimilated by plants.

(iv) It should not produce extra heat which may burn plants.

( v ) It must be stable so that the nutrient element present in it is available to theplants over a long period. It should not be easily leached away from the soil.

(vi) It's physical form should be such that it gets easily and uniformly distributedin soil and keeps the soil loose. It should not be gummy and compact.

F The symptoms of potassium deficiency in fertilizer is that it results in the appear-ance of white, yellow or reddish brown spots on the leaves followed by the edgesbecoming brown, generally in maize, cotton and tobacco plants.

F Due to nitrogen deficiency, the leaf colour becomes light green or yellowish greenand leaves start yellowing or dying.

F The phosphorus deficiency in plants causes poor root growth and purpling of leavesis generally seen in cotton, tobacco and potato crops. Plant growth is stunted, ripen-ing is delayed and fruiting is poor.

F Direct fertilizers are those which are directly assimilated by plants e.g., potassiumand ammonium salts of nitrates and super phosphates.



F Stimulent fert i l izers are those which when added to soil neutralize the soil andmake it loose. These are also called soil improvers or conditioners. They include;humus (organic matter in soils derived from plant residues), gypsum, lime and com-mon salt.

F Mixed fertilizers are those which supply all the three basic elemetns like N, P and K,

F Expression like 4 – 8 – 2 used for mixed fertilizers indicates that it contains 4% N2,

8% P2O

5 and 2% K

2O.

F Farmyard or animal manures supplies N, P and K to the crops as well as improvesthe soil.

F Slaughter house waste also serves as a manure. Blood from slaughter house is col-lected in coagulating tanks with conical bottoms and cooked until coagulated. It isthen dried and powdered. It is sold as such or mixed with other fertilizers.

F Guano is chiefly the excreta of sea fowls mixed with arcasses of young birds andfragments of fish, feathers and sea weeds. It contains nitrogen 2-14% and 20-60%calcium phosphate.

F Tankage. Meat scraps, intestines and carcasses of dead animals are cooked understeam pressure for 10-12 hours. Grease and tellow float on the surface and areremoved. The solids (tankage) are separated from water and ground. It contains11% nitrogen and 12-20% bone phosphate of lime.

F Calcium cyanamide (CaCN2) is a cheap fertilizer which contains about 20.6% nitro-

gen.

F Ammonium sulphate (NH4)

2SO

4 contains 21% nitrogen. It's action depends upon

soil, bacteria and for it's conversion into a nitrate. It's action is slow and it tends toincrease the acidity of soil.

F Basic calcium nitrate, Ca(NO3)

2.CaO contains 17% nitrogen.

F Urea, H2NCONH

2 is a good nitrogenous fertilizer which contains 47% nitrogen.

F Calcium ammonium nitrate (CAN) is also known as nitrochalk. It contains 35%nitrogen. CAN is stable, posesses good physical condition and is easy to handle. It issuperior to (NH

4)

2SO

4 in being more soluble in water and that it prevents develop-

ment of acidity in the soil.



F Super phosphate of lime Ca(H2PO

4)

2.H

2O + CaSO

4.2H

2O consists of a mixture of

nearly two parts by mass of monocalcium phosphate and three parts of gypsum.

It contains about 20% available phosphate. Gypsum in superphosphate of limesupplies calcium as well as sulphur to the soil.

F Double and Triple superphosphates have the amount of available phosphorus muchmore as compared to that in the superphosphate of lime.

F Calcium triple phosphate, CaH4(PO

4)

2 is prepared by reacting a weighed quantity

of Ca3(PO

4)

2 with 54% H

3PO

4 in a mixture.

Ca3(PO

4)

2 + 4H

3PO

4 3CaH

4(PO

4)

2

Rock phosphate Triple superphosphate

F Phosphatic s lag or Thomas slag or Basic s lag is obtained as a biproduct in themanufacture of steel and is probably a double salt of tricalcium phosphate andcalcium silicate.

F Ammoniated phosphates . Calcium phosphate gives H3PO

4 when treated with an

adequate quantity of H2SO

4. However, if one third of H

2SO

4 is substituted by

(NH4)

2SO

4, it gives mono-ammonium phosphate.

Ca3(PO

4)

2 + (NH

4)

2SO

4 + 2H

2SO

4 2NH

4.H

2PO

4 + 3CaSO

3.

The CaSO4 is precipitated and forms a slurry. The solution of monoammonium

phosphate is separated and crystallized. It is stable, crystalline, non hygroscopic andsoluble in water. It contains about 12% nitrogen and 50 - 54% P

2O

5.

F Calcium superphosphate nitrate or nitrophosphate is obtained when Ca3(PO

4)

3 is

treated with HNO3

Ca3(PO

4)

2 + 4HNO

3 Ca(H

2PO

4)

2 + 2Ca(NO

3)

2

Since it contains both N and P in the available form, it is superior to the ordinarysuperphosphate.

F Potash manures show good results on sandy, gravelly or chalky soils. These arespecially used for meadow grass, tobacco, cotton, clovers, coffee, corn and potatoes.They include KCl, K

2SO

4, KNO

3.

F Nitric acid attacks proteins giving a yellow nitro compound called xanthoprotein.Hence, HNO

3 stains the skin and renders wool yellow.

F Hypophosphorus acid, H3PO

2 is a monobasic acid with dissociation constant 1 × 10–2

H3PO

2H + H

2PO

2–1

The other two hydrogen atoms are non ionizable.



F Phosphorus acid, H3PO

3 is a strong dibasic acid.

H3PO

3H + + H

2PO

3–

K1 = 1 × 10–2

H2PO

3– H + + HPO

3–2

K2 = 2 × 10–7

F H3PO

3 reduces salts of Cu, Ag, Au etc. to their respective metals.

F On heating, phosphorus acid, H3PO

3 decomposes into phosphine (PH

3) and phos-

phoric acid (H3PO

4)

4H3PO

3

heat → 3H

3PO

4 + PH

3

F Hypophosphoric acid, H4P

2O

6 is a tetrabasic acid.

H4P

2O

6H

3P

2O

6–1 + H +

K1 = 6.4 × 10–3

H3P

2O

6–1 H

2P

2O

6–2 + H +

K2 = 1.5 × 10–3

H2P

2O

6–2 HP

2O

63– + H +

K3 = 5.4 × 10–8

HP2O

63– P

2O

64– + H +

K4 = 9.4 × 10 –11

F Orthophosphoric acid, H3PO

4 is a tribasic acid ionizing in three stages, as repre-

sented below :

H3PO

4H + + H

2PO

4–1

K1 = 7.5 × 10–3

H2PO

4–1 H + + HPO

4–2

K2 = 6.2 × 10–8

HPO4

–2 H + + PO4

–3

K3 = 1.0 × 10 –13

F Phosphoric acid (H3PO

4) combines with water giving a semihydrate of the formula

2H3PO

4.H

2O.

F Action of heat on orthophosphoric acid, H3PO

4

2H3PO

4

250ºC → H

4P

2O

7 + H

2O

Orthophosphoric Pyrophosphoric

acid acid



H4P

2O

7

600ºC → 2HPO

3 + H

2O

Pyrophosphoric Metaphosphoric

acid acid

F Pyrophosphoric acid, H4P

2O

7 is a tetrabasic acid. It dissociates in four stages with

dissociation constants;

K1 = 1 × 10–1

K2 = 3.2 × 10–2

K3 = 1.7 × 10–6

a n d K4 = 6.0 × 10–9

F Pyrophosphoric acid (H4P

2O

7) is converted into orthophosphoric acid on boiling

wi th H2O.

H4P

2O

7 + H

2O 2H

3PO

4

F Pyrophosphoric acid is a stronger acid than phosphoric acid.

F Glacial phosphoric acid is pure metaphosphoric acid, HPO3.

F Hydrazine (N2H

4) burns rapidly and completely in air with considerable evolution

of heat.

N2H

4 + O

2 N

2 + 2H

2O

∆H = –622 KJ mole–1

The alkylated derivatives of hydrazine are used as potential rocket fuels.

F Hydrazine is a diacid base

N2H

4 (aq) + H

2O N

2H

5+

(aq) +

OH –

Kb1 = 8.5 × 10 –7

N2H

5+

(aq) + H

2O N

2H

6+

(aq) +

OH –

Kb2 = 8.9 × 10 –16

F Hydrazine reduces Fehling solution to red cuprous oxide.

4Cu(OH)2 + H

2N – NH

2 2 Cu

2O + N

2 + 4HCl

Fehling solution Ret ppt.

Cuprous oxide

F Hydrazine reduces FeCl3 to FeCl

2.

4FeCl3 + H

2N – NH

2 4FeCl

2 + N

2 + 4HCl

Ferric Ferrous

chloride Chloride



F Hydrazine reduces potassium iodate to potassium iodide.

4KIO3 + 3H

2N – NH

2 2KI + 6H

2O + 3N

2

F Hydrazine reduces salts of Pt, gold and silver to metallic state.

PtCl4 + N

2H

4Pt + N

2 + 4HCl

4AuCl3 + 3N

2H

44Au + 3N

2 + 12HCl

4AgNO3 + N

2H

44Ag + N

2 + 4HNO

3

F The dipole moment of hydrazine is 1.85 Debye.

F Hydrazoic acid (N3H) is dangerously explosive acid and decomposes as

2N3H 3N

2 + H

2

∆H = –51.5 KJ mole–1

F The strength of hydrazoic acid (N3H) is in comparison to that of acetic acid

(CH3COOH).

N3H N

3–1 + H +

Ka = 1.8 × 10–5

CH3COOH CH

3COO– + H +

Ka = 1.8 × 10–5

F Arsenic can be detected by :

( i ) Marsh test

(ii) Gutzeit test

(iii) Fleitmann test

(iv) Reinsch test

F The physical constants of the hydrides of group 15 are given as under :

Physical NH3

PH3

AsH3

SbH3

BiH3

constant

Melting –77.8 –133.5 –116.3 –88 –

point

(ºC)

Boiling point –34.5 –87.5 –62.5 –18.4 16.8(ºC)

Bond angle 107.3º 93.6º 91.8º 91.3º –

H – X – H

Bondlength 1.02 1.42 1.52 1.71 –

H – X (Å)

Heat of formation –46.1 –9.6 66.4 145.1 277.8

(KJ mole–1)



F Scheele 's green is formed during the detection of arsenic.

To the solution of arsenic compound are added a few drops of CuSO4 and then

NaOH till it is alkaline. A bright green precipitate of Scheele's green i.e., CuHAsO3,

Copper arsenite is formed.

H3AsO

3 + Cu2+ + 2OH – CuHAsO

3 + 2H

2O

Scheele's greem

F Marsh test for the detection of arsenic proceeds as under :

Pure zinc (free from arsenic) is placed in a flat bottom flask fitted with a droppingfunnel and a delivery tube carrying CaCl

2 tube and a jet. Some lead acetate is also

added to the CaCl2 tube. Pure dilute H

2SO

4 is added through the dropping funnel

and H2 evolved is lighted at the end of the jet. The jet tube is heated in the middle.

If no black deposit is obtained in the jet, it shows that both zinc and dilute H2SO

4

are free from arsenic.

The substance suspected to contain Ar is run into the flask. If a black deposit isobtained in the jet which is soluble in sodium hypochlorite, it indicates the presenceof arsenic.

Z n + H2SO

4ZnSO

4 + 2H

AsCl3 + 6H AsH

3 + 3HCl

2AsH3

heat → 2As + 3H

2

F Neutron activation analysis is used to detect traces of arsenic (10 –10 to 10–12 gm).Arsenic nucleus contains 33 protons and 42 neutrons. When it is bombareded byneutrons, the stability of the nucleus vanishes and a radioactive isotope of arsenic isobtained. By measuring the radioactive emission, it is possible to determine thetraces of arsenic present in the sample.

F Reaction of arsenious chloride (AsCl3) with water. With insufficient amount of H

2O

,

arsenious chloride forms arsenious oxychloride while with excess of water it formsarsenious oxide.

AsCl3 + 2H

2O AsCl(OH)

2 + 2HCl

Insufficient Arsenious oxychloride

4AsCl3 + 6H

2O As

4O

6 + 12HCl

Arsenious oxide

F Arsenic exists in three allotropic forms :

( i ) Grey metallic form

(ii) Yellow non-metallic form

(iii) Black arsenic form



F Par i s g reen or Cupr ic-ace toarseni te , (CH3COO)

2.Cu.Cu(AsO

2)

2 o r

Cu4(CH

3CO

2)

2(AsO

2)

2 is used as an insecticide.

F Fowler's solution is a solution of sodium arsenite. It is used as a tonic in veterinarypractice and also as a weed killer.

F Arsenious acid, (H3AsO

3) forms three types of salts :

( i ) Ortho arsenites, e.g., K3AsO

3.Cu

3(AsO

3)

2.

(ii) Meta arsenites, e.g., NaAsO2

(iii) Pyro arsenites, e.g., Na4As

2O

5.

F Arsenious oxide is used

(i) In the manufacture of pyrex glass

(ii) As an insecticide and weed - killer and for poisoning vermin.

(iii) For preserving the skins of animals.

(iv) In medicine as a tonic and for certain skin diseases.

( v ) In iodometric titrations as a primary standard.

F Arsenic is used

(i) In medicines and as a tonic.

(ii) For making alloys and lead shots.

(iii) In agriculture, the compounds of arsenic are used as sprays and cattle dips fordestroying insects.

F Occurrence of arsenic. It's most important minerals are :

( i ) Arsenical pyrite or mispickle, FeAsS

(ii) Orpiment, As4S

6.

(iii) Realgar, As4S

4.

( iv) Cobaltite, CoAsS.

(v ) Nickel glance, NiAsS.

F Lead arsenate, PbHAsO4 is used as an insecticide for spraying fruit trees.

F Stibnite, Sb2S

3 is the sulphide ore of Sb. In earlier times it was used in medicines

and for darkening of eyebrows.

F Antimony (Sb) exists in three allotropic forms :

( i ) Common or crystalline metallic variety.

(ii) Yellow or α -antimony.

(iii) Explosive antimony.



F Antimony is used for the preparation of

(i) Type metal

(ii) Babbit metal

(iii) Britannia metal

(iv) Pewter .

F Tartaremetic is chemically potassium antimony tartarate.CH(OH).COO(SbO) |CH(OH).COOK(Tartaremetic)

It is used as an emetic in small doses while large doses are poisonous. Large quanti-ties of it are used as mordants. It is used for the treatment of Kala-azar and suchother tropical diseases.

F Antimony is a metalloid.

F Charcoal cavity test for antimony. A white incrustation and a white brittle bead isformed.

F When a tin foil is placed in an antimony salt solution, a velvety deposit of Sb isformed on the tin foil.

F Antimony salt solution when diluted gives a white precipitate of (SbOCl) which issoluble in tartaric acid

SbCl3 + H

2O SbOCl + 2HCl

F Acidified antimony salt solution gives an orange ppt. of Sb2S

3 which is soluble in

yellow ammonium sulphide.

Sb2S

3 + 3(NH

4)

2S 2(NH

4)

3SbS

3

Yellow ppt. Ammonium-thioantimonate

F Bismuth has only one allotropic form with melting point 544 K, boiling point 1837K and density 9.8 g/cm3 at 298 K.

F The four known oxides of bismuth are :

( i ) Bismuth monoxide, BiO or Bi2O

2

(ii) Bismuth trioxide, Bi2O

3

(iii) Bismuth tetraoxide, Bi2O

4

(iv) Bismuth pentaoxide, Bi2O

5

F Bismuth is used

(i) In the construction of thermopiles

(ii) In the manufacture of fusible alloys which are used for making fuses forelectrical apparatus, fire alarms, automatic water sprinklers etc.



OXYGEN FAMILY

F The volatility of hydrides of 16 group elements increases from H2O to H

2S. The

boiling points of hydrides of group 16 are given as under :

Hydride H2O H

2S H

2S e H

2T e H

2Po

Boiling point(ºC) 100ºC -6ºC 0.75ºC -41.5ºC -1.8ºC

F Metal oxides are usually basic in nature, non metal oxides are acidic and the oxides ofthe elements which lie in between metals and non metals are amphoteric.

(i) Acidic oxides : CO2, SO

2, P

4O

10, NO

2, N

2O

5 etc.

(ii) Basic oxides : Na2O, CaO, K

2O, Cs

2O etc.

(iii) Amphoteric oxides : Al2O

3, ZnO

F The basic nature of oxides increases in a group and acidic nature decreases. Forexample, the basic nature of alkali metal oxides increase as

Li2O < Na

2O < K

2O < Rb

2O

F The basic nature of oxides decreases in a period and acidic nature increases. Forexamples,

Na2O, MgO, Al

2O

3, SiO

2, P

4O

10, SO

3, SO

3, Cl

2O

7

Basic Amphoteric Acidic

F Tailing of mercury is due to the formation of mercury oxide when Hg reacts withozone

2Hg + O3 → Hg

2O + O

2

As a result of it, mercury looses it's meniscus and starts sticking to the glass.

F Bleaching action of ozone is due to it's ability to bleach colour of indigo and othervegetable colours by oxidation

Vegetable colouring matter + O3 → Colourless oxidized matter + O

2

F The bleaching action of ozone and H2O

2 is permanent and is due to oxidation while

that of SO2 is temporary and is due to reduction.

F Ozone has angular structure. The bond angle is 116º 8' and oxyen -oxygen bondlength is 128 Pm.

F Due to polar character, water has high dielectric constant (82) and is the best solventto dissolve ionic compounds.



F Temporary hardness of water is due to the presence of bicarbonates of Ca and Mg and Permanenthardness is due to the presence of sulphates and chlorides of Ca and Mg.

F Calgon is a trade name given to sodium polymetaphosphate Na2 [Na

4 (PO

3)

6]. It is

generally employed for softening of hard water.

F 10 V H2O

2 means that one mole of that H

2O

2 at N.T.P. evolves 10 ml. of oxygen gas.

F H2O

2 is heavier than water (density = 1.44 g/cm 3) ; it's melting point is 272.4 K ;

decomposes at 413 K ; boiling 423.2 K ; heat of dissociation - 196 KJ mole –1 anddissociation constant at 293 K is 1.55 x 10–12.

F H2O

2 is used to restore the colour of old lead paintings which have been blackened

due to the formation of PbS by the action of H2S present in the air.

H2O

2 → H

2O + [O]

PbS + 4[O] → PbSO4

PbS + 4H2O

2 → PbSO

4 + 4H

2O

Black White

F Antichlor action of H2O

2 is due to its tendency to reduce the excess of chlorine from

bleaching powder to HCl

H2O

2 + Cl

2 → 2HCl + O

2

F Perhydrol is H2O

2 solution used for washing wounds, teeth and ears.

F H2O

2 has a non planer structure, O – O bond length is 147..5 Pm and both O – H

bonds lie in different planes. The interplaner angle is 94.6º.

F SO2 gas is dried by bubbling the mixture through conc. H

2SO

4. It is not dried over

quick lime (CaO) as it reacts with it to form calcium sulphite.

CaO + SO2 → CaSO

3

F Some oxy acids of sulphur are :

Acid Chemical formula

H2S O

2Sulphoxylic acid

H2S O

3Sulphurous acid

H2S O

4Sulphuric acid

H2S

2O

3Thiosulphuric acid

H2S

2O

5Disulphurous acid



H2S

2O

7Disulphuric acid

H2SO

5Peroxomonosulphuric acid

(Caro's acid)

H2S

2O

8Peroxy disulphuric acid

(Marshall's acid)

H2S

nO

4Polythionous acid

H2S

nO

6Polythionic acid

F Nordhasen's acid

2H2SO

4 + 2NO

2 → H

2O +

32

O2 + 2(NO)SO

3H

(Conc. ) Nordhasen's acid

F OF2 has oxygen atom in + 2 oxidation state. It has v shaped structure with bond

angle 103º - 2'. It is prepared by passing F2 gas rapidly through NaOH solution.

2F2 + 2NaOH → 2NaF + H

2O + OF

2

F Sodium thiosulphate Na2S

2O

3.5H

2O is prepared by the following methods :

(a) By boiling sodium sulphite with sulphur

Na2SO

3 + S Boil → Na

2S

2O

3

(b) By boiling sulphur with NaOH.

4S + 6NaOH Boil → Na2S

2O

3 + 2Na

2S + 3H

2O

(c) By passing SO2 into Na

2S solution.

3Na2S + 3SO

2 ———→ 2Na

2S

2O

3 + S

(d) By spring's reaction

Na2S + Na

2SO

3 + I

2 heat → Na

2S

2O

3 + 2NaI

F Na2S

2O

3.5H

2O on heating decomposes to give SO

2, H

2S and S.

F Na2S

2O

3 solution on treatment with dilute silver nitrate solution gives a white ppt.

which changes to yellow, brown and finally black due to the formation of silversulphide, Ag

2S .

S2O

32– + 2Ag + ———→ Ag

2S

2O

3

White ppt.

Ag2S

2O

3 + H

2O ———→ Ag

2S + H

2SO

4

Black



F Concentrated Na2S

2O

3 does not give a white ppt. with AgNO

3. This is because silver

thiosulphate formed is readily soluble in excess of sodium thiosulphate forming asoluble complex.

3S2O

32– + Ag

2S

2O

3 ———→ 2 [Ag(S

2O

3)

2]–3

Soluble

F Sodium thiosulphate is oxidized by Cl2 to sodium sulphate

Na2S

2O

3 + Cl

2 + H

2O ———→ Na

2SO

4 + 2HCl + S

F Sodium thiosulphate is oxidized to sodium tetrathionate Na2S

4O

6 by I

2.

2Na2S

2O

3 + I

2 ———→ Na

2S

4O

6 + 2NaI

Sodium tetrathionate

This reacton forms the basis of iodometric estimation of Cr2O

72– and Cu2+ salts.

F Sodium thiosulphate reacts with FeCl3 solution to form a violet coloured solution

of ferric thiosulphate.

3S2O

32– + 2Fe3+ ⇔ Fe

2(S

2O

3)

3

Violet

The violet colour disappears quickly due to the reduction of feric chloride by S2O

32–

ions,

2Fe3+ + 2S2O

32– ———→ 2Fe2+ + S

4O

62–

F Sodium thiosulphate reduces cupric salts to cuprous salts.

2CuCl2 + 2Na

2S

2O

3 ———→ 2CuCl + Na

2S

4O

6 + 2NaCl

F Sodium thiosulphate reduces auric salts to aurous salts.

AuCl3 + 2S

2O

32– ———→ AuCl + S

4O

62– + 2Cl–

AuCl + 2S2O

32– ———→ [Au(S

2O

3)

2]3– + Cl–

F The atomic radius for 16 group elements (in Pm) are given as under :

O S S e T e P o

74 103 119 142 168

F The melting and boiling points of 16 group elements (in K) are given as under :

O S S e T e P o

Melting point 54 393 490 725 527

Boiling point 90 718 958 1263 1235

F At 298 K, the density of 16 group elements (in g/cm 3) is given as under :

O S S e T e P o

1.32 2.06 4.34 6.25 9.14



F The electronegativity values of 16 group elements are given below :

O S S e T e P o

3.5 2.5 2.4 2.1 2.0

F The first two I.E. values (in KJ mole –1) for 16 group elements are given below :

O S S e T e P o

I .E .1

1314 1000 941 869 813

I .E .2

3388 2251 2045 1790 -

F The first two electron affinity values (in KJ mole –1) for 16 group elements are givenbelow :

O S S e T e P o

E.A.1

142 200 195 190 -

E.A.2

–780 –590 –420 –295 -

F The relative abundance in earth's crust (in PPm) for 16 group elements are given asunder :

O S S e T e P o

455000 340 0.05 0.001 -

F The lattice energies of the oxides of alkaline earth metals (in KJ mole –1) are given asunder :

Metal Lattice energy, KJ mole –1

M g O –3923

C a O –3517

S r O –3312

B a O –3120

F The oxidation state of oxygen can be –2, +2 and –1. The other members of the 16group family show oxidation states +2, +4 and +6.

F The allotrpic forms of oxygen are :

( i ) Oxygen, (O2)

(ii) Ozone, (O3)

Both of these forms are non-metallic in nature.

F The allotropic forms of suiphur are; (i) Rhombic sulphur (ii) Monoclinic sulphur(iii) Plastic sulphur

F The allotropic forms of selenium are ; (i) Red (non metallic) (ii) Grey (metallic)



F The allotropic forms of tellurium are : (i) non metallic (ii) metallic

F The allotropic forms of polonium are metallic in nature. They are : (i) α -Polonium(ii) β -Polonium.

F Bond energies of the 16 group elements (M – M) bonds (in KJ mole –1J are given asunder :

B o n d Bond energies (KJ mole–1)

O – O 142

S – S 226

Se – Se 172

Te – Te 126

F The oxidation state of oxygen in OF2 is +2.

F The paramagnetic character of oxygen is best explained by molecular orbital theory.

F Oxygen is used

(i) In hospitals for giving artificial respiration to persons suffering frompneumonia or gas poisoning.

(ii) When mixed with nitrous oxide or ethylene, it is used for producing anaesthesia.

(iii) In oxy hydrogen or oxy acetylene flame for welding and cutting.

(iv) In iron and steel industry to increase the oxygen content of the blast in Bessmerand open hearth processes.

( v ) In carbon dust cartridges used in place of dynamite in coal mining.

(vi) In the fuels for rockets.

F Oxygen gas is absorbed by alkaline pyrogallol.

F Atomic oxygen is obtained when oxygen gas is passed at about 1 mm pressure througha discharge tube.

O2 O + O

∆H = 489.6 KJ mole –1

It is chemically more reactive than O2.

F Fe3O

4 is called ferrous ferrite and may be written as Fe (FeO

2)

2. It may be assumed

to be made up of FeO and Fe2O

3.

F Mn3O

4 is called manganous manganite and may be written as Mn (MnO

2)

2. It may

be assumed to be made up of MnO and MnO2.



F Pb3O

4 is called plumbous plumbite and may be written as Mn(MnO

2)

2. It is as-

sumed to be made up of MnO and MnO2.

F Acidic oxides are those which dissolve in water forming acids and neutralize alka-lies. They are also called acid anhydrides and are generally the oxides of non metals.

Examples : B2O

3, SiO

2, CO

2, N

2O

3, N

2O

5, P

2O

3, SO

2, Cl

2O

7 and I

2O

5.

Metallic oxides of higher oxidation states (e.g., CrO3, V

2O

5 and Mn

2O

7 etc.) are also

acidic oxides.

F Basic oxides are of two types :

( a ) Essentially covalent. These are generally oxides of transition with formula MOand M

2O

3. They are essentially covalent, non volatile, have giant molecular

structure and are insoluble in water.

(b ) Essentially ionic. These are generally oxides of alkali earth metals. They reactwith water to give basic solution. These might be oxides (Na

2O, CaO, BaO),

peroxides (Na2O

2 and BaO

2) and super oxides (KO

2, RbO

2 etc).

F Amphoteric oxides dissolve both in acids and alkalies. For example :

( i ) ZnO, giving Zn2+ ions and zincates, [Zn(OH)2]2–

(ii) Al2O

3, giving Al 3+ ions and Al(OH)

4–1 ions

(iii) SnO, giving stannous salt Sn2+ and stannites, [Sn(OH)4]2–

(iv) SnO2 giving stannic salts Sn4+ and stannates, [Sn(OH)

6]2–

F Neutral oxides are those which are neutral towards litmus e.g., carbon monoxide(CO), water (H

2O), nitrous oxide (N

2O) and nitric oxide (NO).

F The decomposition of ozone is catalysed by the substances like MnO2, platinum

black, copper oxide etc.

F Ozone is a pale blue gas with a characteristic strong smell.

F Ozone when inhaled in small quantities causes headache and nausea but in largequantities it is poisonous.

F Liquid ozone is of deep blue colour (boiling point 160.6 K).

F Solid ozone forms violet black crystals (melting point 23.3 K).

F Ozone is heavier than air and is slightly soluble in water but is more soluble inturpentine oil, glacial acetic acid and CCl

4.



F Tests of ozone

(i) It turns starch iodide paper blue.

(ii) A clean silver foil is blackened by ozone.

(iii) It turns benzidine paper brown and tetramethyl base paper violet.

( iv) Tailing of mercury. Mercury looses it's meniscus in contact with ozone andsticks to the surface of glass due to the formation of Hg

2O.

F Ozone is used

(i) As germicide and disintectant for sterilizing water and improving theatmosphere of crowded places like railways, mines and cinema halls.

(ii) For bleaching oils, ivory, flour and starch etc.

(iii) For the manufacture of KMnO4 by the oxidation of K

2MnO

4

(iv) In the manufacture of artificial silk and synthetic camphor.

F T h e O4 s pec i e s has been detected in liquid oxygen. It may consist of dimerized

oxygen molecules.

F In the native state sulphur occurs in the volcanic regions of Sicily, Italy, Japan,South America, Russia and Iceland.

F Eggs, proteins, garlic, onions, mustard, hair and wool contain traces of sulphur.

F Sulphur is a pale yellow brittle solid crystalline in nature.

F Sulphur is insoluble in water but readily soluble in CS2 and sparingly soluble in

alcohol and ether.

F Sulphur is an excellent insulator.

F Action of heat on sulphur

(i) Ordinary sulphur melts at 387.5 K to a pale yellow liquid.

(ii) On heating above 387.5 K instead of being becoming more mobile it growsthicker and more viscous and it's colour changes to reddish brown and finallyblack.

(iii) At 453 K, it becomes so viscous that it cannot be poured out by inverting thetest tube.

(iv) The viscosity goes on decreasing above 453 K till 718 K and it flows freely andbegins to boil giving heavy red vapours with molecular formula S

8.

( v ) The vapours formed above dissociate into S4 on further heating and then S

2 and

then S at 2273 K. These changes are reversed on cooling.



F Allotropic modifications of sulphur are :

( i ) Rhombic, octahedral or α -sulphur. It has meiting point 385.8 K and density2.06 g/cm 3. It is soluble in CS

2. This is the variety stable at ordinary

temperature.

(ii) Monoclinic, prismatic or β-sulphur. It has a melting point 393 K and dnesity1.98 g/cm 3. It is stable above 369 K and passes into α -sulphur below it. It issoluble is CS

2.

(iii) Plastic sulphur of λ-sulphur, It's density is 1.95 g/cm 3. Plastic sulphur isobtained by pouring boiling sulphur in cold water when rubber like mass isobtained. The rubber like mass is a super cooled liquid and as such has nosharpmelting point. It is unstable and passes into rhombic sulphur on standing.It is unstable and passes into rhombic sulphur on standing. It is insoluble inCS

2.

( iv) Milk of sulphur is obtained by boiling milk of lime with sulphur anddecomposing the calcium pentasulphide thus formed with HCl when milk ofsulphur is precipitated as white amorphous precipitate.

3Ca(OH)2 + 12S 2CaS

5 + CaS

2O

3 + 3H

2O

Milk of lime Calcium-

pentasulphide

2CaS5 + CaS

2O

3 + 6HCl 3CaCl

2 + 3H

2O + 12S

Milk of sulphur

It is soluble in CS2 and is largely used in medicines.

F Colloidal sulphur is obtained when H2S gas is bubbled through HNO

3 or sodium

thiosulphated solution is treated with dilute HCl

2HNO3

2NO2 + H

2O + O

H2S + O H

2O + S

__________________________________________

2HNO3 + H

2S S + 2NO

2 + 2H

2O

_____________________________________________

Na2S

2O

3 + 2HCl 2NaCl + SO

2 + S + H

2O

F Kipp's apparatus is used to prepare H2S gas in the laboratory from iron sulphide by

the reaction with dilute HCl or dilute H2SO

4.

FeS + H2SO

4 FeSO

4 + H

2S

F H2S gas is better purified by absorbing the gas in magnesium oxide suspension in

water and heating it later to 333 K.

MgO + 2H2S Mg(SH)

2 + H

2O

Mg(SH)2 + H

2O Heat

→ MgO + H2S



F H2S gas is dried by passing over CaCl

2 or P

2O

5.

F H2S gas is not dried by passing through conc. H

2SO

4 as the acid is reduced by the

gas.

F H2S gas is poisonous in nature. When inhaled in small quantities, it produces se-

vere headache whereas larger amounts cause death.

F The boiling point of H2S is 213 K and melting point 190 K.

F The sulphides which are precipited in acidic solution and constitute group II inqualitative inorganic analysis are :

HgS, CuS and PbS Black

Bi2S

3B r o w n

As2S

3, CdS and SnS

2Yellow

Sb2S

3Orange

S n S Chlocolate

F The sulphides which are precipitated in ammonical solution containing NH4Cl and

constitute group IV in qualitative analysis are :

CoS and NiS Black

Z n S White

M n S Flesh coloured or Pink

F Yellow ammonium sulphide, (NH4)

2 S

x is also called ammonium polysulphide.

F Tests of H2S

(i) It has an offensive rotten egg smell.

(ii) It turns lead acetate paper black.

Pb(CH3COO)

2 + H

2S PbS + 2CH

3COOH

Black ppt.

(iii) It gives a violet colour with an ammonical solution of sodium nitroprusside.

Na2 [Fe(CN)

5NO] + H

2S Na

4 [Fe(CN)

5NOS]

Sodium-nitroprusside Violet

F Polysu lph ides . Solutions of alkali sulphides, ammonium sulphides and alkalineearth metal sulphides readily dissolve in sulphur by forming polysulphides, e.g.,Na

2S

2, Na

2S

3, Na

2S

5, (NH

4)

2S

x.



F Yellow ammonium sulphide is used for the separation of group (IIA) elements fromgroup II B. This is because the sulphides of As, Sb and Sn form soluble complexeswith yellow ammonium sulphide and pass into the solution whereas sulphides ofHg, Pb, Bi, Cu and Cd remain unaffected.

As2S

3 + 3(NH

4)

2S

2 2(NH

4)

3AsS

4

Ammonium-thioarsenate

Sb2S

3 + 3(NH

4)

2S

2 2(NH

4)

4SbS

4

Ammonium-thiontimonate

SnS + (NH4)

2S

2 (NH

4)

2SnS

2

Ammonium-thiostannate

F Calcium phosphide is used as fungicide and insecticide in agriculture.

F SO2 is used for fumigation, bleaching and needed for the manufacture of sulphuric

acid and thiosulphates.

F Sulphur compounds like CS2, P

2S

3 are extensively used in match industry.

F Sulphur compounds find use in the manufacture of Gun powder and fire-works.

F Calcium bisulphite is used in paper industry.

F A mixture of sulphur with lead arsenate or lime is used as a fungicide in agriculture.

F Sulphur is used internally or as sulphur ointment in skin eruptions.

F Sulphur dyes are used for dyeing hosiery.

F Vulcanisation of rubber involves the heating of the rubber mixture (with sulphur asone of the ingredients) to a definite temperature for a definite time. It removes thesticky qualities of rubber, makes it more elastic and gives the article produces apermanent shape.

F The oxides of sulphur are given as under :

Formula N a m e Oxidation state of sulphur

SO Sulphur monoxide + 2

SO2

Sulphur dioxide + 4

SO3

Sulphur trioxide + 6

S2O

7Sulphur heptaoxide + 7



F Sulphur monoxide (SO) is prepared by heating a mixture of SO2 and S at 425 –

475.

SO2 + S

425 475− →

K 2SO

It can also be prepared by the action of silver on thionyl chloride.

SOCl2 + 2Ag SO + 2AgCl

F Sulphur dioxide (SO2) is prepared :

( i ) By the burning of sulphur in air.

S + O2 SO

2

(ii) By the burning of sulphides in air.

2ZnS + 3O2

2ZnO + 2SO2

4FeS2 + 11O

2 2Fe

2O

3 + 8SO

2

(iii) In the laboratory,it is prepared by heating copper turnings with conc. H2SO

Cu + 2H2SO

4 CuSO

4 + SO

2 + 2H

2O

F SO2 reduces KMnO

4 to MnSO

4

2KMnO4 + 5SO

2 + 2H

2O K

2SO

4 + 2MnSO

4 + 2H

2SO

4

F SO2 reduces potassium dichromate to Cr

2(SO

4)

3

K2Cr

2O

7 + H

2SO

4 + 3SO

2 K

2SO

4 + Cr

2(SO

4)

3 + H

2O

F SO2 reduces potassium iodate of iodine.

2KIO3 + 5SO

2 + 4H

2O 2KHSO

4 + 3H

2SO

4 + I

2

F SO2 bleaches colouring matter to colourless matter. The bleaching action of SO

2 is

by reduction and takes place in presence of water.

SO2 + 2H

2O H

2SO

4 + 2H

Colouring matter + 2H Colurless matter + H2O

The bleaching action of SO2 is temporary.

F Structure of SO2.

SO2 is a triatomic molecule. The sulphur oxygen bond distance is 143 Pm and

angle OSO is 120º. The molecule has a net dipole moment indicating it's V-shaped



structure. The OSO angle of 120º suggests that sulphur atom is sp2 hybrilized inwhich the two hybrid orbitals are used to form bonds with oxygen atoms and thethird orbital is occupied by a lone pair. Expeiments indicate that two S – O bondlengths in SO

2 are identical and considerably shorter than the expected S – O single

bond which is indicative of multiple bonding. There is pπ – pπ bonding and as wellas pπ – dπ bonding due to the overlap of filled pπ orbitals of oxygen with the vacant3d orbitals of sulphur.

F Sulphur tr ioxide (SO3) is a white crystalline solid with melting point 290 K and

boiling point 318 K.

F SO3 is prepared by the direct oxidation of SO

2 with atmospheric oxygen in presence

of finally divided Pt or V2O

5 at a pressure of 2 atm. and temperature 700 K.

2SO2 (g) + O

2 (g) 2SO

3 (g)

F SO3 reacts with water to produce H

2SO

4 and a large amount of heat is evoived.

SO3 + H

2O H

2SO

4 + heat

F SO3 acts as a strong Lewis acid towards a number of inorganic and organic com-

pounds .

(C6H

5)

3P + SO

3 (C

6H

5)

3P.SO

3

(C6H

5)

3AsO + SO

3 (C

6H

5)

3Ars.SO

3

F Structure of SO3

( a ) In the gas phase, SO3 is a planar triangular molecule with sulphur atom in sp 2

hybridization state.

O

S

120ºOO

143 Pm

In order to account for the equivalency of all the S – O bonds and short S – Odistance of 143 Pm, SO

3 may be considered as a resonance hybrid involving pπ - pπ

S – O bonding along with additional pπ - dπ bonding.

(b ) In the solid phase, SO3 polymerizes to puckered rings or to more stable layer

structure as shown :



O|S

O|

S|O

O O

O|

S|O

O

O

Ring structure

O|S

O |O

Layer structure

O|S

O |O

O|S

O |O

O

1743. Sulphur heptaoxide (S2O

7) is a colourless liquid which freezes at 275K. It is prepared

by passing silent electric discharge through a mixture of SO2 and O

2

4SO2 + 3O

2

Electric

Disch e →

arg 2S

2O

7

F The oxoacids of sulphur are given as under :N a m e Formula Structure

Sulphurous acid H2S O

3

Sulphuric acid H2S O

4

Peroxomono-sulphuric H2S O

5

acid (Caro's acid)

Thiosulphuric acid H2S

2O

3

Dithionic acid H2S

2O

6

Disulphuric acid H2S

2O

7

Peroxodi-sulphuric H2S

2O

8

acid (Marshall's acid)



F Sulphurous acid (H2SO

3) is prepared by dissolving SO

2 in water

SO2 + H

2O H

2S O

3

F H2SO

3 is a strong reducing agent. It reduces halogens to halogen acids,

permanganates to manganous salts.

F H2SO

3 exists in two forms which are always in equilibrium with one another.

(Symmetrical sulphurous acid) (Unsymmetrical sulphurous acid)The unsymmetrical form cotaining S – H bond explains the reducing character ofH

2S O

3

F The sulphite ion (SO3

2–) , the anion of H2SO

3 has a pyramidal structure with S

atom in Sp3 hybridization and all the S – O bonds are of equal bond length (134Pm).

F Sulphites and Bisulphites. Sulphurous acid is a dibasic acid and gives rise to twoseries of salts :( i ) normal salts with formula M

2SO

3 called sulphites.

(ii) acid salts with formula MHSO3 called bisulphites.

F Sulphur trioxide (SO3) exists in three forms :

( i ) α – sulphur trioxide is long, transparent ice like needle form with melting point290 K and boiling point 318 K.

(ii) β – sulphur trioxide is formed when α – sulphur trioxide is kept below 298 K. Itforms silky, asbestons like needles with melting point 305 K.

(iii) γ – sulphur trioxide is obtained by completely drying the β -form. It sublimeswithout melting at ordinary temperature. It resembles the b-form in appearance.It melts at 335 K under a pressure of 2.5 atmosphere.

F SO3 is used

(i) For drying gases.(ii) In the manufacture of H

2SO

4 and oleum.

F SO3 gives an addition product, chlorosulphonic acid with HCl.

SO3 + HCl → Cl.SO

2.OH

Chlorosulphonic acid

F Favourable conditions for the preparation of SO3 in the contact process for the

manufacture of H2SO

4 are

2SO2 + O

22 S O

3∆H = – 189 KJ–1 mole



( i ) The temperature must be low. The experimentally determined optimumtemperature is 670 – 720 K.

(ii) V2O

5 is used as a catalyst.

(iii) A pressure of 2 atmosphere is required.(iv) Excess of oxygen in the gaseous mixture favours the formation of SO

3.

F Badiche process for the manufacture of H2SO

4 involves platinized asbestos as catalyst

but being costly and easy poisoning, it's use is abandoned.

F Grillo 's process for the manufacture of H2SO

4 involves the use of finally divided

platinum deposited on MgSO4

F Mannheim process for H2SO

4 manufacture involves the use of a mixture of ferric

oxide and cupric oxide as catalyst.

F Arsenic pur i f ier in the contact process for the manufacture of H2SO

4 contains

gelatinous ferric hydroxide resting on shelves. It removes any arsenic oxide presentin the gases passing.

F H2SO

4 is a colourless syrupy liquid (density 1.84 g cm –3 at 288 K)

F H2SO

4 boils at 611 K.

F H2SO

4 cannot be concentrated beyond 98.3 percent by boiling, due to the formation

of azeotropic mixture.

F 100% pure H2SO

4 can be prepared by dissolving SO

3 in dilute H

2SO

4

F Concentrated H2SO

4 fumes strongly in moist air.

F H2SO

4 forms two series of salts; an acidic salt (MHSO

4) and simple salt (M

2SO

4).

F Charring of wood, paper, sugar and preparation of CO from oxalic acid or formicacid justify the dehydrating nature of H

2SO

4.

HCOOH H SO conc2 4 . → CO + H2O

Formic acid

(COOH)2

H SO

Conc2 4 →

.CO + CO

2 + H

2O

Oxalic acid

C12

H22

O11

H SO

Conc2 4 →

. 12C + 11H

2O

Sucrose Charcoal



F The high affinity of H2SO

4 towards water is due to the formation of hydrates, e.g.,

H2SO

4.H

2O ; H

2SO

4.2H

2O etc.

F H2SO

4 reacts with PCl

5 to form SO

2Cl

2. It justifies the presence of two – OH

groups in H2SO

4.

+ PCl5→ + POCl

3 + HCl

Sulphuric acid Chlorosulphonic acid

+ PCl5

→ SO2Cl

2 + POCl

3 + HCl

Sulphury l chloride

F H2SO

4 is used

(i) In fertilizer industry(ii) In petroleum refining(iii) In the preparation of HCl, HNO

3, H

3PO

4 etc.

(iv) In the preparation of dyes and drugs.( v ) For pickling which involves the removing of oxide layer from the surface ofmetals before enamelling, electroplating or galvanization.(vi) In the manufacture of explosives like dynamite, TNT etc.(vii) In the extraction of copper.(viii) In the preparation of rayons, photographic films, rubber and lacquers.

F Action of heat on the sulphates of iron

2FeSO4

heat → Fe2O

3 + SO

2 + SO

3

Ferrous sulphate B r o w n

Fe2( S O

4)

3heat → Fe

2O

3 + 3SO

3

B r o w n

F Sulphuric acid contains the anion SO4

2– which is tetrahedral and sulphur involvesSp3 hybridization.

F H2S

2O

4 is called Hyposulphurous acid, Hydrosulphurous acid or Dithionous acid.

F Hyposulphurous acid is a dibasic acid nearly as strong as H2SO

4. It forms salts

known as hyposulphites.

F H2S

2O

8, Marshall's acid or Peroxodisulphuric acid or Perdisulphuric acid is prepared

by the anodic oxidation of 50% H2SO

4.

H2S O

4H+ + HSO

4–



At anode,2HSO

4– – 2 e → 2 H S O

4→ H

2S

2O

8

It can also be prepared by the sulphonation of H2O

2

H2O

2 + 2ClSO

3H → H

2S

2O

8 + 2HCl

F H2SO

5, Caro's acid or Peroxosulphuric acid is prepared by reacting one mole of a

peroxide with one mole of chlorosulphonic acidH

2O

2 + ClSO

3H → H

2SO

5 + HCl

F Thionyl chlor ide (SOCl2) is considered as the acid chloride of sulphurous acid,

H2SO

3 .

F Thionyl chloride (SOCl2) is prepared by the reation of PCl

5 on SO

2 or Na

2SO

3.

SO2 + PCl

5 → SOCl

2 + POCl

3

+ 2PCl5

→ SOCl2 + 2POCl

3 + 2NaCl

On commercial scale, it is prepared by the action of SO3 on sulphur monochloride,

S2Cl

2.

SO3 + S

2Cl

2→ SOCl

2 + SO

2 + S

F Sulphate (SO4

2–) is estimated as BaSO4

gravimetrically.

F CLAUSTHALITE is chemically lead selenide, PbSe

F LIEMANNITE is chemically HgS.

F Selenium occurs in four allotropic modifications.(i) Amorphous selenium, a bright red solid soluble in CS

2 and the solution deposits

red crystals.(ii) Vitreous selenium, a black glassy mass which can be electrified by friction. Itsdensity is 4.2 gcm –3 and it contains randomly arranged Se

8 molecules of various

lengths in its structure.(iii) Monoclinic selenium, an orange red or dark red solid. Its density is 4.5 gmcm –3.This modification consists of Se

8 ring molecules with Se – Se distance = 232 Pm.

(iv) Metallic selenium, the most stable form of selenium. Its density is 4.8 gmcm –3

and its structure consists of Zigzag Se8 chains.

F Selenium boils at 958 K giving out dark yellow vapours which condense to give apowder resembling flowers of sulphur.

F Selenium is a good conductor of electricity when exposed to light but a feeble one indark.



F Selenium is used in photoelectric cells.

F Selenium is a poor conductor of electricity at ordinary temperature but becomes agood conductor at 475 K.

F SeO2 has SO

2 type of structure in the gaseous form. However, in the solid form it

consists of nonplanar infinite chains.

F Selenium is used(i) In glass industry as decolorizer and in the manufacutre of ruby glass.(ii) In photoelectric cells.(iii) In rubber industry to make rubber more abrasive.(iv) SeO

2 is used as a catalyst in a number of reactions.

( v ) Cadmium selenide is used in the manufacture of paints and pigments.(vi) Selenium is used in xerography.

F Selenious acid, H2SeO

3, is obtained by the action of HNO

3 on Se or by dissolving

SeO2 in water.

SeO2 + H

2O → H

2SeO

3

F Se len i c ac id , H2SeO

4, is prepared by the oxidation of selenious acid in aqueous

solution with Cl2, Br

2 or lead dioxide.

H2SeO

3 + Cl

2 + H

2O → H

2SeO

4 + 2HCl

H2SeO

3 + PbO

2→ H

2SeO

4 + 2PbO

It is a colourless crystalline solid with melting point 331 K.

F Selenates are the salts of selenic acid. They are isomorphous with the correspondingsulphates.

F Selenium te t rachlor ide , SeCl4 , is prepared by the action of Cl

2 on selenium

monochloride or by treating SeO2 with PCl

5.

Se2Cl

2 + 3Cl

2→ 2SeCl

4

6SeO2 + 6PCl

5→ 6SeCl

4 + P

4O

10 + 2POCl

3

It is a yellow solid which sublimes at 464 K and is readily hydrolysed by water.

F Analytical detection of selenium(i) On heating, selenium compounds give off a typical offensive odour.(ii) When a solution of selenious acid is treated with SO

2, a red precipitate of selenium

is formed.

F Tellurium was discovered in 1782 by Mullervon Riechenstein and named by Klaprothin 1798 from the Latin tellus meaning earth.



F Some important minerals of tellurium are(i) Petzite : (Ag, Au)

2 Te (ii) Hessite : Ag

2Te (iii) sylvanite : (Au, Ag) Te

2

F The principal source of tellurium is anode mud from electrolytic refining of copperwhich is a source of selenium.(i) The allotropic forms of tellurium are :(ii) A black amorphous form precipitated from telluric acid by SO

2.

(iii) A stable form which is a grey crystalline solid with a metallic lustrue.

F The atomic mass of tellurium is 127.6 which is higher than that of iodine whichfollows it in the periodic table. This is because of the fact that iodine occurs as apure element of mass number 127 while tellurium consists of several isotopes ofmass numbers 122, 123, 124, 125, 126, 128 and 130, the last two predominating.

F Tellurium resembles both S and Se in chemical properties.

F Tellurium is added to lead to improve its resistance to heat, mechanical shock andcorrosion.

F Tellurium crystals are used in the detectors for wireless telephones.

F Tellurium in Na2S is used in photography as a toning agent.

F Tellurium is used in colouring porcelain and glass.

F Tellurization is a process which doubles the mileage obtained from gasoline. Diethyltelluride is added in small amounts to gasoline to be used in high compressionmotors.

F Polonium is a radioactive metal which occurs in radium minerals, e.g., pitch blendecontains about 5 × 10 –9% Po.

F 210Po84

is prepared by bombarding natural bismuth with neutrons.209Bi

82 (n, r) → 210Bi

83→ 210Po

84 + 0e

–1

F 210Po84

has a half life period of 138.4 days.

F 210Po84

is an α -emitter and is used as a source of α-particles

F Polonium has both of its crystalline forms, cubic and rhombohedral as metallicforms.

F Polonium mainly exists in + 2 and + 4 oxidation states.

F The melting point of polonium is 527 K, boiling point 1235 K and density 9.14gcm –3.



HALOGEN FAMILY

F Some of the examples of polyhalides are :

ICl2

–, IBr2

–, BrCl2

–, ClF2

–, ICl4

–, BrF4

–, IF6

–, BrF6

–,

ICl2

+, IBr2

+, BrF2

+, IF4

+, ClF4

+, BrF4

+, IF6

+, BrF6

+, ClF6

+.

F Pseudohalides are uninegative groups which show certain characteristics of halideions. For example, Cyanide (CN–), Cyanate (OCN–), Thiocyanate (SCN –), Selencyanate(SeCN–), Azide (N

3–), Aziothio crbonate (SCSN

3–) and isocyanate (ONC–)

F Chlorine monoxide Cl2O, is having angular structure with bond angle 111º, Cl is in

sp3 hybridization state.

F Oxy acids of halogens :

Acid Chemical formula

Hypohalous acid HOX (HOCl, HOBr, HOl)

Halous acid HXO2 (HClO

2, HBrO

2, HlO

2)

Halic acid HXO3 (HClO

3, HBrO

3, HlO

3)

Perhalic acid HXO4 (HClO

4, HBrO

4, HlO

4)

F The reducing nature of halogen acids decreases as

HI > HBr > HCl > HF

F The acidic strength of halogen acids in aqueous solutions follows the increasing ordr :

HF < HI < HBr < HCl

but in the gaseous state HF < HCl < HBr < HI

F Flourine shows predominantly – 1 oxidation state. Other halogens show oxidationstates – 1, + 1, + 3, + 5 and + 7.

F The atomic radius of 17 group elements (in Pm) are given below :F Cl B r I72 99 114 133

F The ionic radii of 17 group elements (in Pm) are given as under :F Cl B r I133 184 196 220

F The electronegativities of 17 group elements are given below :F Cl B r I4 3.0 2.8 2.5



F The ionization energies of 17 group elements (in KJ mole –1) are gives as under :F Cl B r I1681 1256 1143 1009

F The electron affinity values (in KJ mole –1) for 17 group elements are given below :F Cl B r I333 349 325 296

F The melting and boiling points for halogens (in K) are given below :F

2Cl

2B r

2I

2

Melting point 54 172 266 387Boiling point 85 239 333 458

F The densities of 17 group elements (in gmcm –3) are given below :F Cl B r I1.513 1.655 3.187 3.960(85 K) (203 K) (273 K) (493 K)

F The colour of 17 group elements are :Fluorine Pale yellowChlorine Greenish yellowBromine Reddish brownIodine Violet

F The bond energies (in KJ mole –1) for halogens are :F

2Cl

2B r

2I

2

158.8 242.6 192.8 151.1

F The enthalpies of vaporization (in KJ mole –1) for halogens areF

2Cl

2B r

2I

2

158.8 242.2 192.8 151.1

F The bond distance (in Pm) for different halogens are :F

2Cl

2B r

2I

2

143 199 228 266

F The enthalpies of fusion (in KJ mole –1) for 17 group elements are given below :F

2Cl

2B r

2I

2

0.51 6.41 105.7 15.52

F The heat of dissociation (in KJ mole –1) for 17 group elements are :F

2Cl

2B r

2I

2

159 243 193 151



F The heat of hydration (in KJ mole –1) for 17 group elements are :F

2Cl

2B r

2I

2

515 381 347 305

F The melting and boiling points of different halogen acids are given below :H

2F

2H C l H B r H I

Melting point (K) 190 162 187 222.2Boiling point (K) 292.5 189 206 237.5

F AgF is soluble in water while AgBr and AgI are insoluble.

F CaF2 is insoluble in water while CaCl

2, CaBr

2 and CaI

2 are soluble.

F The hydrogen bond length in HF is 155 Pm.

F The standard reduction electrode potentials of 17 group elements (in volts) areF

2Cl

2B r

2I

2

2.87 1.26 1.09 0.54

F Fluorine constitutes nearly 0.08 percent of lithosphere.

F The main sources of flurine are fluorspar (CaF2), Cryolite (AIF

3.3NaF) and apatite

[CaF2.3Ca

3(PO

4)

2] .

F Traces of fluorine occur in sea water, some mineral springs, bones, teeth, blood,milk, plants etc.

F Moissan, in 1886 prepared fluorine from KHF2.

F Chlorine constitutes nearly 0.19 percent of lithosphere.

F On a commercial scale, chlorine is prepared by the electrlysis of brine solution.

F Chlorine is also obtained as a byproduct in the manufacture of sodium, magnesiumand calcium.

F Bromine constitutes nearly 0.01 precent of lithosphere. It occurs in combined statein sea water and dry salt lakes.

F Iodine constitutes nearly 10–4 percent of lithosphere.

F Iodine is having the main source Kelp, viz., the ash obtained on burning sea weedswhere it occurs as iodides and chile salt petre in which it occurs as iodates.

F Astatine is prepared by bombarding bismuth with α -particles.209Bi

83 + 4He

2 → 211At

85 + 2(1n

0)

F Polyhalides are formed by the association of halogens with halide ions e.g., I3

–1 ,Br

3–1 , Cl

3–1 , ICl

2–1, ICl

4–1. Only Fluorine does not form F

3–1 due to the absence of

d-orbitals.



F Some important properties of hydrogen halides are tabulated below :

F Pseudohalides are uninegative groups which show certain characteristics of halide ions.

F Some of the pseudo halide ions and pseudohalogens are given as under :Pseudohalide ions Formulae Pseudohalogens Formulae

Cyanide CN– Cyanogen (CN)2

Cyanate OCN– – –Thiocyanate SCN– Thiocyanogen (SCN)

2

Selenocyanate SeCN– Selenocyanogen (SeCN)2

Azide N3

– – –Azidothiocarbonate SCSN

3– Azido carbon disulphide (SCSN

3)

2

Isocyanate ONC– – –



F Interpseudohalogen compounds are formed between two different pseudohalogens e.g., CN.N3,

CN(SCN), CN (SeCN).

F Iodine shows electropositive character. It has a metallic lusture and has a tendency to lose electronsto form I+ and I+3

A. Evidence for the existence of I+ ion(a) Molten ICl is a good conductor of electricity. On electrolysis, a mixture of I

2 and Cl

2 is

liberated at anode while only iodine is evolved at cathode. This suggests that ICI ionizes as2ICl I+ + ICI

2–

(b) On electrolysis of ICN in pyridine, only I2

is liberated at cathode. This suggests that ICNionizes as

ICN I+ + CN–

(c) The formation of the complex [I(Py)2] NO

3 also supports the electropositive nature of iodine.

B. Evidence for the existance I3+ ionMolten ICl

3 conducts electricity. On electrolysis, it gives a mixture of I

2 and Cl

2 at both the

electrodes. This suggests that ICl3 ionizes as :

2ICI3

ICI2

+ + ICI4

–

The ICl2

+ and ICI4

– ions contain I+3 ions.

F Reaction of fluorine with alkalies(a) 2OH– + 2F

2→ F

2O + 2F– + H

2O

(Dilute)(b) 4OH– + 2F

2→ 4F– + O

3 + 2H

2O

(Conc.)

F Chlorine was discovered by Scheele in 1774. He prepared it by heating HCl (muriatic acid) withMnO

2.

F Phosgene is chemically COCl2.

F Tear gas is chemically CCl3. NO

2.

F Mustard gas is chemically ClC2H

4 – S – C

2H

4Cl

F Tests for chlorine(a) It is a greenish yellow gas with irritating smell.(b) It turns starch iodide paper blue.(c) It bleaches litmus paper and indigo solution.

F Bromine was discovered by Balard in 1826.F Bromine occurs only in the combined state as bromides of sodium, potassium and manganese in

sea water, certain mineral springs and stassfurt deposits.

F Bromine is fairly soluble in water, more soluble in organic solvents like alcohol, ether, CHCl3 and

CS2.



F Bromine water when cooled to 273 K forms bromine hydrate, Br2. 10 H

2O.

F Reaction of alkalies with bromine(a) In cold : 2OH– + Br

2→ Br– + BrO– + H

2O

(b) In hot : 6OH– + 3Br2

→ 5Br– + BrO3

– + 3H2O

F Tests of bromine(i) Bromine gives pungent smelling vapours dark red in colour which do not turn FeSO

4 solution

black.(ii) It turns starch paper yellow and starch iodide paper blue.(iii) It dissolves in CS

2 to give orange colour to the organic layer.

F Iodine was discovered by Bernard Courtois.

F Iodine occurs only in the combined state as iodides, in sea water, in sea weeds and sponges. Largeamount of iodine are present in caliche (crude chile salt petre).

F Iodine is a steel grey solid which sublimes on heating giving beautiful violet colour vapours. Therhombic crystalline plates have a metallic lusture.

F Iodine is slightly soluble in water but much more soluble in KI due to the formation of KI3.

KI + I2 → KI

3

The solution behaves as a simple mixture of KI and I2.

F Iodine is insoluble in water but becomes soluble if a small amount of KI is added to it. This is due tothe formation of highly soluble complex Kl

3.

F Tincture of iodine is a mixture of iodine, KI and absolute alcohol.

F Action of alkalies on iodine. In cold dilute solution of an alkali, iodine reacts to give a hypoioditewhich hydrolyses further to yield hypoiodous acid

2OH– + I2→ IO– + I– + H

2O

or 2NaOH + I2

→ NaI + NaIO + H2O

NaIO + H2O → HIO + NaOH

NaOH + I

2 → NaI + HIO

In this reaction, iodine undergoes disproportionation (i.e., simultaneous oxidation and reduction).In hot solutions, iodine reacts with alkalies to give iodates.

6OH– + 3I2

→ 5I– + IO3

– + 3H2O

2NaOH + I2

→ [NaI + NaIO + H2O] × 3

3NaIO → NaIO3 + 2NaI

6 NaOH + 3I

2→ 5NaI + NaIO

3 + 3H

2O

Sodium iodate



F Reaction of iodine with NH3 forms nitrogen tri-iodide which is a black explosive powder

2NH3 + 3I

2→ NI

3.NH

3 + 3HI

8NI3.NH

3→ 5N

2 + 9I

2 + 6NH

4I

F Tincture of iodine is prepared by dissolving 10 g each of Iodine and KI in 100 ml. of water and

making the solution to 300 ml. It is used as a disinfactant and analgesic.

F Iodimetry is a process of estimating reducing substances by the use of standard iod solution

2S2O

32– + I

2→ S

4O

62– + 2I–

F Iodometry is a process of indirect estimation of oxidizing agents involving the liberation of iodine

and subsequent volumetric estimations of the latter. In this method, an oxidizing agent reacts withKI to set free an equivalent quantity of iodine which is titrated against S

2O

32–

2Cu2+ + 4I– → Cu2I

2 + I

2

White ppt.I

2 + S

2O

32– → S

4O

62– + 2I–

Tetrathionate ion

F Tests of iodine

(i) Characteristic violet colour of it's vapours serves as a test for iodine.

(ii) It gives deep blue colour with starch solution.

F The longest lived isotope of astatine is 211At85

with a half life period of 8.3 hours.

F The bond dissociation energy of astatine is 117 KJ mole–.



F A comparison of the properties of halogens is given in the table below :

F Action of silica and glass. Strong solution of HF attacks glass readily forming silicon (IV)fluoride which gives complex fluosilicic acid, H

2SiF

6 with excess HF.

SiO2 + 2H

2F

2→ SiF

4 + 2H

2O

SiF4 + H

2F

2→ H

2SiF

6

This is called etching of glass.



F Hydrofluoric acid (HF) is a colourless liquid with boiling point 292.5 K and freezing point 170.5 K.

F HF fumes strongly in air.

F HF is monomeric above 353 K (1 atm.)

F Solid HF has zigzag chain structure.d(H – F) = 92 Pm

d (H – – F) = 157 Pm< FFF = 120.1º

F The distinguishing tests for halide ions are given below :



F NaF is used as an insecticide for ants, cockroaches etc., and its 1% aqueous solution is sprayed onwoolen to make them moth proof. If also prevents chicken lice.

F The binary halogen oxygen compounds are given below :Fluorine Chlorine Bromine IodineOF

2Cl

2O Br

2O I

2O

4

ClO2

BrO2

I2O

5

O2F

2Cl

2O

6BrO

3I

4O

9

Cl2O

7

F OF2 has a V-shaped structure with bond angle 103º – 18´ and O involves sp3 hybridization.

F O2F

2, Dioxygen difluoride has structure similar to H

2O

2.

F Chlorine monoxide (Cl2O) can be regarded as an anhydride of hypochlorous acid (HOCl). It has

an angular structure as shown :

F Chlorine dioxide, (ClO2) is a mixed anhydride. Its molecule is through to contain a three electron

bond coupled with an electron pair bond. Its structure is considered to be a resonance hybrid of thefollowing two strucutres :

The three electron bond accounts for the shorter bond length and its paramagnetic nature.

F ClO2 does not show any tendency to get dimerized although it contains an odd electron. This is

because the odd electron is not fully localized on the central atom unlike in other odd electronmolecules like NO

2.

F Dichloro heptaoxide (Cl2O

7) is assumed to be the anhydride of perchloric acid (HClO

4). It is the

most stable chlorine oxide and is a strong oxidizing agent. It has the structure O3Cl – O – ClO

3

with tetrahedral chlorine as shown below :

F Iodine pentaoxide (I2O

5) is considered to be the anhydride of iodic acid (HIO

3). It has a planer

structure with each oxygen atom sp2 hybridized.



F Some oxoacids of halogens are tabulated below :Oxidation Chlorine Bromine lodine Name of Name of Thermal Oxidisingstate of acid salt stability powerhalogen and

acid strength+ 1 HClO HBrO HIO Hypohalous Hypo- Increases Decreases

halite+ 3 HClO

2– – Halous Halite Increases Decreases

+ 5 HClO3

HBrO3

HIO3

Halic Halate Increases Decreases+ 7 HClO

4HBrO

4HIO

4Perhalic Perhalate Increases Decreases

H5IO

6Increases Decreases

F The acidic strength of the oxoacids of halogens decreases in the following orderHClO

4 > HClO

3 > HClO

2 > HClO

The chlorine oxyanion in which the central atom has highest oxidation number will have maximumnumber of oxygen atoms for participation in the extension of the π-bond. Thereby the charge onthe ion is delocalized which greatly stabilizes the ion and thus decreases its tendency to accept aproton i.e., causes the ion to be very weak base with the result that the strength of the acid increases.

F The oxidizing power of oxoacid anions of halogens decreases asClO– > ClO

2– > ClO

3– > ClO

4–

F The thermal stability of oxoacids of halogens decreases in the order :HClO

4 > HClO

3 > HClO

2 > HClO

F HClO4 is a stronger acid than H

2SO

4 due to more oxidation state of Cl than S and hence more

delocalization.

F The acidity of oxoacids of different halogens having the same oxidation number decreases with theincrease in atomic number of the halogen.

HClO > HBrO > HIOThis is because as the atomic number of the halogen increases. It's electronegativity decreases butsize increases. As a result, the tendency to lose a proton in water decreases. This makes the acid aweaker acid.

F Fluorine does not form oxoacids.

F Hypohalites (OX–) are the anions of hypohalous acid and have the structure as shown belwo :



F Halous acids have halogen in +3 oxidation state. Chlorous acid (HClO2) is prepared by the action

of H2SO

4 on Barium chlorite.

Ba(ClO2)

2 + H

2SO

4 → BaSO

4 + 2HClO

2

F Chlorite ion (ClO2

–1) has the angular structure

F Chloric acid (HClO3) on heating under pressure forms perchloric acid (HClO

4)

3HClO3 → HClO

4 + 2O

2 + Cl

2 + H

2O

F Paraperiodic acid (H5IO

6) on heating in vaccum at 373 K forms metaperiodic acid (HIO

4)

2H5IO

6

353

3 2

K

H O →

−H

4I

2O

9373 K → 2HIO

4 + H

2O

Paraperiodic Dimesoperiodic Metaperiodic acid acid acid

F CF4 is used as a manometric liquid at low temperature.

F CCl2F

2, dichloro difluoromethane is widely used in refrigerators because of its low boiling point,

nontoxic and non-corrrosive nature.

F Chlorofluoro carbons on polymerization give rise to stable oils, waxes and a greases, suchlubricants are knwon as fluorolubes. They find application as heat transfer media and dielectricmedia.

F Tetra fluoroethylene (C2F

4) on plymerization forms polytetrafluoro ethylene commerically known

as teflon which is inert to chemical attack.

F Some physical properties of interhalogen compounds are given below :Type Compound M.P.°C B.P.°C Trouton's Appearance

constantXX'

1ClF – 156 – 100 28.0 colourless gasBrF – 33 – 20 20.5 pale brown gasIF – – – detected

spectroscopicallyBrCl – 65 – –ICl 27.2 (α) – 5 – ruby red crystal

13.9 (β) 97 – brown red crystalIBr 36 116 – black solid

XX'3

ClF3

– 76 12 23.1 colourless gasBrF

38.8 126 25.7 yellow green liquid

IF3

– 28 (dec) – yellow powder



ICl3

101/16 atm 64 (sub) – orange solidXX'

5IF

59.6 98 – colourless liquid

BeF5

– 61.3 41 23.7 colourless liquidClF

5– 196 – – –

XX'7

IF7

45 5 26.4 colourless gas

F Thermal stability of inter-halogen compounds fall in the orderIF > BrF > ClF > ICl > IBr > BrCl

F Cationic halogens(a) The existence of I+

3 and I+

5 in 100%. H

2SO

4 has been confirmed when I

2 and HIO

3 is dissolved

H2SO

4 in the molar ratio 7 : 1, the equilibrium,

HIO3 + 7I

2 + 8H

2SO

4 5I+

3 + 3H

3O+ + 8HSO–

4

is established. Furthermore, the conductivity remains the same if more I2 is added. Evidently. I

5+ is

formed.(b) Blue coloured ion I+

2 is obtained when I

2 in HSO

3F is oxidized with S

2O

6F

2.

2I2 + S

2O

6F

2 → 2I

2+ + 2SO

3F–

(c) Fresh solution of I2

+ in HSO3F becomes bright red near the freezing point of the acid. This is

due to the formation of I4

+

(d) Brown coloured Br3

+ can be obtained by the oxidation of Br2 with S

2O

6F

2. Further oxidation

leads to the formation of Br2

+ .(e) Evidence for the existence of Cl

3+ and Cl

2+ is weaker but a yellow solid Cl

3+ [ArF

6]– has been

made from Cl2, ClF and ArF

5 at 200 K. It decomposes rapidly at room temperature.

(f) Some triatomic interhalogen cations have been established. These are : ClF2

+, BrF2

+, ICl2

+

and Cl2F+.

F Some important physical properties of halogen oxides are given below :



F Some important oxoacids of halogen oxides are given below :



NOBLE GASES

F The relative abundance in dry air by volume (PPm) of different noble gases is :H e N e Ar K r X e R n5.24 18.18 93.40 1.14 0.09 traces

F The melting points (K) for different noble gases are given as under :H e N e Ar K r X e R n– 24.6 83.3 115.9 161.3 202.0

F The boiling points (K) for different noble gases are given as under :H e N e Ar K r X e R n4.2 27.1 87.3 119.7 165.0 211

F The atomic radii (Pm) for different noble gases are :H e N e Ar K r X e R n93 112 154 167 190 –

F The vander wall's radii of different noble gases (Pm) are given below :H e N e Ar K r X e R n120 160 191 200 220 –

F The ionization energy values (KJ mole –1) for differen noble gases are given below :H e N e Ar K r X e R n2372 2080 1520 1351 1170 1037

F The enthalpies of vaporization, ∆H vap. (KJ mole–1) for noble gases are given below :H e N e Ar K r X e R n0.08 1.74 6.52 9.05 12.65 8.1

FCC

P

V for noble gases is 1.67.

F The refractive index, dielectric constant and other physical properties of noble gasescorrespond to their monoatomic nature.

F The most important source of noble gases is atmosphere in which theyare presentin following proportions by volume and mass :

Element Percentage by volume Percentage by massHe 0.0006 0.000037N e 0.0015 0.001Ar 0.932 1.285K r 0.0001 0.00028X e 0.00001 0.00004



F Helium is present to the extent of 2 percent in natural gas found in the Unitedstates and Canada.

F Helium is also present in the minerals of radioactive elements uranium and thoriume.g., clevite, uranite, thorianite, monazite, pichblende etc.

F Henry Cavendish (in 1785) found that when electric sparks are passed throughpurified air mixed with excess of oxygen over KOH (to absorb the oxides of nitrogenformed) and the excess of oxygen was removed by means of P

2S

5 a small bubble of

air is left which does not disappear, even if the sparks may be passed for a longertime.

F In september 1891, Rayleigh found that the density of nitrogen insolated from airby passing purified air repeatedly over heated copper was about 0.5 percent higherthan the density of nitrogen obtained from chemical compounds like ammoniumnitrite or urea. He found the density of the atmospheric nitrogen to be 1.25717gper litre while that of the chemical nitrogen to be 1.25207 g per litre. Ramsaysuggested that the cause of this difference was the presence of some heavy gas in theatmospheric nitrogen. To test this hypothesis Rayleigh proceeded in collaborationwith Ramsay. The oxygen and nitrogen present in a quantity of purified air wereremoved by passing it alternately over heated copper (which removes oxygen formingthe oxide and heated magnesium which removes nitrogen forming the nitride). Theresidual gas which formed nearly one percent of the volume of the air taken wasfound to give a spectrum which did not coincide with that of any other of elementhitherto known. The vapour density oft he gas was found to be about 20 which gavethe molecular mass as 40. This gas was named argon from the Greek word, meaninglazy and its higher density accounted for the atmospheric nitrogen being moreheavy. This gas argon was later found to be a mixture of severlal gases, all beingchemically inert.

F During a total eclipse in August 1868 Lockyer observed a bright yellow line nearthe D

1 and D

2 lins of sodium in the chromosphere of the sun and called it the D

3

line.. He named the element causing this line helium from the Greek work helios,meaning the sun since he believed it to exist only on the sun and not on earth.Twenty-one years later Hi lderbrand obtained a gas by heating in vaccum or byheating with an acid certain uranium-containing minerals. He considered this gasto be nitrogen.

F Ramsay repeated Hildebrand's experiments with the mineral clevite and obtained agas by heating it alone in vacuum or by heating it with dilute sulphuric acid. Heremoved the nitrogen by the usual methods and examined the residual gasspectroscopically when he observed a new bright yellow line not coinciding with theyellow lines of sodium. He sent a sample of the gas to Crookes, a specialist inspectroscopy, who identified the yellow line to be identical with that of helium



discovered by Lockyer in sun's chromosphere. This proved the existence of heliumon earth. Its density was found to be 2 and atomic mass 4.

F In 1896, Jul iot Thomson suggested the desirability of inserting a zero groupconsisting of six elements with atomic masses 4, 20, 36, 84, 132 and 212. Thisidea made Ramsay and Travers very enthusiastic aboutthe discovery of the remainingelements. In 1898, they carried out systematic fractionation of liquid argon underdifferent reduced pressures. The first fraction was found to contain a new elementwhich they named neon (new). Its vapour density was found to be 10.1 which gaveit a molecular mass of 20.2 . The final fraction gave spectra of two new gases whichwere named krypton (hidden) and xenon (stranger). They isolated these two gasesby the fractination of a large volume of liquid air and also studied their properties.Their atomic masses were determined to be 80 and 128, respectively.

F The sixth member of the zero group was discovered in 1900 by Dorn as one of thedisintegration products of radium and was named radon or nitron.

F In Dewar's method, the separation of noble gases are summerized below :

F The viscosity of He is extremely low, about 1

100th of hydrogen gas.

F The thermal conductivity of He is very high about 800 times that of copper at roomtemperature.

F The lifting power of He is 92% that of hydrogen.



F Helium is used for filing airships and balloons for meteorological observations.

F Mixture of He with O2 under pressure is supplied to sea divers for respiration.

F Helium is used to provide inert atmosphere in the welding of metals or alloys thatare easily oxidized.

F Helium (density 2) is lighter than that of air (density 14.4) and is used for inflatingthe tyres of big aeroplanes.

F Neon is used to produce glow sign boards.

F Argon mixed with 26% N2 is used in gas filled electric lamps and in radio valves

and tubes.

F Krypton and xenon have not been prepared in large quantities and have not beenemployed for a useful purpose.

F Radon is used in radioactive research and in radiotherapy for the treatment ofcancer.

F Theoretical importance of the noble gases( a ) The discovery of isotopes began with the experiments on Ne which was the first

to be separated into atoms of different masses.(b ) The noble gases proved to be the key elements in the elucidation of some aspectsofthe atomic structure and the electronic theory of valence and chemical activity.

F XeF2 oxiddizes H

2 to HF.

XeF2 + H

2 → Xe + 2HF

F XeF2 oxidizes H

2O to HF and O

2

2XeF4 + 2H

2O → 2Xe + 4HF + O

2

F XeF4 is hydrolysed by alkalies to F—

ions and O

2.

2XeF4 + 4OH – → 2Xe + 4F– + 2H

2O + O

2

F XeF2 oxidizes HCl to Cl

2, IO

3– to IO

4– , Ag (I) to Ag (II), Co (II) to Co (III) and

Ce(III) to Ce (IV)

F XeF2 reacts with F

2 to form XeF

4

XeF2 + F

2 → XeF

4

F The reactions of XeF2 with SO

3 and C

2H

4 are given as under :

2XeF2 + 4SO

3 → 2Xe + O

2 + 2S

2O

5F

2

2XeF2 + 2C

2H

4 → CH

2F.CH

2F + CHF

2.CH

3 + 2Xe



F XeF2

is a colourless, crystalline solid and is the least volatile fluoride of xenon. Itmelts at 400 K.

F XeF4 is a colourless solid with melting point 387 K.

F XeF4 sublimes on heating in a current of N

2 giving colourless vapours.

F XeF4 dissolves in liquid HF without any action and the poor conductivity of the

solution is due to HF.F XeF

4 oxidizes KI to iodine.

XeF4 + 4KI → 2I

2 + 4KF + Xe

F XeF4 disproportionates in water.

6XeF4 + 12H

2O → 2XeO

3 + 24HF + 4Xe + 3O

2

F XF4 fluorinates SF

4

XeF4 + 2SF

4 → Xe + 2SF

6

F XeF6 is a colourless crystalline solid which turns yellow at 316 Kand melts at 320.7

K to give yellow solid.

F XeF6 reacts readily with silica and cannot be stored in glass vessels.

2XeF6 + SiO

2 → 2XeOF

4 + SiF

4

F XeF6 dissociates to the extent of 30% in HF and the solutions are conduting.

XeF6 + HF XeF

5+ + HF–

2

F XeF6 reacts with CsF and RbF to form heptafluoroxenates.

XeF6 + CsF → CsXeF

7

Caesium-heptafluoro-xenateXeF

6 + RbF → RbXeF

7

RbXeF7 decomposes at 293 K while CsXeF

7 at 323 K.

F XeF6 is hydrolysed with water in different stages.

XeF6 + H

2O → XeOF

4 + 2HF

XeF6 + 2H

2O → XeO

2F

2 + 4HF

XeF6 + 3H

2O → XeO

3 + 6HF

F Xenic acid is chemically H6XeO

6.

F XeO3 is a white non-volatile solid and is explosive

F An aqueous solution XeO3 is weakly acidic.

XeO3 + H

2O H + + HXeO

4–1

XeO3 + 3H

2O H + + H

5XeO

6–1



F XeO3 undergoes disproportionation in e aqueous solution.

4XeO3 + 12OH – → Xe + XeO

64– + 6H

2O

Perxenate ion

F Xenontetraoxide (XeO4) is formed when sodium perxenate (Na

4XeO

4.6H

2O) reacts

with conc. H2SO

4 at 268 K. It is a yellow solid at low temperature and is unstable

at room temperature.

F XeOF4 is a colourless volatile liquid which solidifies at 25 K.

It is formed by the partial hydrolysis of XeF6 with H

2O as well as by the reaction of

XeF6 with silica.

XeF6 + H

2O → XeOF

4 + 2HF

2XeF6 + SiO

2 → 2XeOF

4 + SiF

4

F Gas hydrates form an important class of clatherates. These are formed when wateris solidifed in presence of certain atomic or small molecular gases (e.g., Ar, Kr, Xe,Cl

2, SO

2, HCl). The structures of these clatherates are much less dense than that of

ice and are assumed only if guest atoms or molecules are present.

F Clatherates or Cage compounds or Host guest compounds are the compounds formedby certain crystalline compounds like p-Quinol by trapping noble gas particles Ar, Krin the cavities of their hydrogen bonded crystal lattice. Only weak Vander Waals'sforces exist between different clatherates.



CHEMICAL BONDING

F Fazan's Rules :

(i) The cations with smaller size have high polarizing power, i.e., they cause polarisa-tion of electronic charge cloud of an anion to a greater extent.

(ii) The anions with larger size have high polarizability i.e., their electronic chargecloud can be deformed easily.

(iii) For effective polarization there should be a high charge on the cation or theanion or both .

(iv) The polarization of ions results in a high electron charge concentration betweenthe two nuclei. This results is the formation of a covalent bond called polar covalentbond.

To sum up, smaller cations and larger anions favour the formation of a covalentbond.

F Metallic bond is the force of attraction which binds a metal atom (Kernel) to a numberof electrons within it's sphere of influence.

F Points of differences between a metallic bond and a covalent bond.

(i) The valency electrons in a covalent bond are localized and a covalent bond isdirectional in nature and the valency electrons in a metallic bond are spread all overthe crystal and as a result, metallic bond is non directional in nature.

(ii) Metallic bonds are weaker than covalent bonds.

F Hydrogen bond is the attractive force which binds hydrogen atom of one moleculewith highly electronegative atom (such as F, O or N) of another molecule of the sameor different. Hydrogen bond is weaker than covalent bond. It's strength lies between8-45 kJ mol–1.

F Acetic acid and Benzoic acid exist as dimers in benzene due to intermolecular hydro-gen bonds.

F H2O is a liquid while H

2S is a gas. This is due to more strong intermolecular hydro-

gen bonding in H2O due to small size and more electronegativity of oxygen.

F H2SO

4 is a high boiling syrupy liquid. This is due to strong intermolecular hydrogen

bonds.

F Ice is lighter than H2O due to intermolecular hydrogen bonding giving tetrahedrally

bonded open cage structure to ice.



F Maximum density of H2O is at 277 K.

F Orthonitro phenol is more volatile (lesser boiling point) than meta and paranitrophenols because in ortho nitrophenol due to intramolecular hydrogen bondingassociation is prevented.

F Hydrogen bonding explains the stability of secondary structure of proteins.

F Hydrogen bonding plays an important role in making wood fibres more rigid and thusmaking it an article of great utility to meet requirements of housing furnitrure etc.

F According to VSEPR theory :

(i) For maximum stability of a molecule, the hybrid orbitals occupied by electrons inthe valence shell of the central atom should be so arranged in space so that they lie asfar away from one another as possible.

(ii) The geometry of a molecule depends upon the arrangement of orbital with respectto one another around the central atom, i.e., on the angles which these orbitals makewith one another in the space around the central atom. Since, there can be only onedefinite orientation of orbitals corresponding to minimum energy, a molecule of agiven substance has invariably a definite geometry.

(iii) If the central atom is surrounded only by hybrid orbitals containing shared pairof electrons i.e., bond pairs and there are no hybrid orbitals containing lone pair inthe valency shell, the molecule has a regular geometry. If however, the central atom isalso surrounded by one or more hybrid orbitals containing lone pair of electrons inthe valency shell, the geometry of the molecule is distorted.

F The geometry of a molecules BeF2, BeH

2, BeCl

2, ZnCl

2, HgCl

2 is linear and the

central atom is in sp hybridization state.

F The geometry of molecules, BF3, BCl

3, AlCl

3, BH

3 is trigonal planaer and the central

atom involves sp2 hybridization.

F The molecules CCl4, SiF

4, CH

4 have tetrahedral geometry and the central atom in-

volves sp3 hybridization.

F The molecules PF5, PCl

5, SbCl

5 have trigonal bipyramidal geometry and the central

atom involves d sp3 hybridization.

F SF6 involves d2 sp3 hybridization and has octahedral geometry while IF

7 involves d3

sp3 hybridization and has pentagonal bipyramidal geometry.



F SnCl2 molecule involves sp2 hybridization and has V-shaped geometry.

F Both H2O and NH

3 involve sp2 hybridization and H

2O is V-shaped while NH

3 i s

pyramidal.

F SF4 involves sp3d3 hybridization and geometry is distorted trigonal bipyramidal; ClF

3

has sp 3d hybridization and is T-shaped; XeF2 has sp3d hybridization and is linear ;

XeF4 has sp 3d2 hybridization and is square planer, IF

5 has sp 3d2 hybridization and is

square pyramidal ; PCl3 has sp3 hybridization and is pyramidal ; H

2O, SeCl

2, and

NH2 have sp3 hybridization and are V-shaped ; ICl

2–1 has sp3d2 hybridization and is

having linear geometry ; ICl4 has sp 3d2 hybridization and is square planer.

F The geometries of species are tabulated below :

Examples Type of Geometry of

hybridization involved the molecule

BeF2, CO

2 [Ag(NH

3)

2] + s p Linear

BCl3, BH

3, CO

32–, HCHO, NO

3–1 sp 2 Trigonal planer

SnCl2, PbCl

2s p 2 V-shaped

CH4, NH

4+, SO

42–, ClO

4–1, ClO

3–1 s p 3 Tetradehedral

NH3, PX

3s p 3 Trigonal pyramidal

H2O, SeCl

2, NH

2s p 3 V-shaped

PF5, Fe(CO)

5s p 3d Trigonal bipyramidal

SF4, TeBr

4s p 3d Irregular tetrahedral

ClF3

s p 3d T-sheped

XeF2, ICl

2— s p 3d Linear

XF6, [SbF

6]– sp 3d 2 Octahedral

IF5, ClF

5, [SbF

5]2– sp 3d 2 Square pyramidal

XeF4, ICl

4sp 3d 2 Squareplanar

IF7

sp 3d 3 Pentagonal bipyramidal

F The geometry of an ion depends upon-

(i) The number of sigma bonds involved in bonding atoms.

(ii) The number of lone pairs of electrons present around the central atom.

F The bonds present in a molecule do not influence the geometry of a molecule.



F Shapes of Molecules and Ions Having Pair (s) AtomGeneral Example Shape Orbital Electrontype type pair arrangement

, H3O+ , PF

3Trigonal sp3 Tetrahedralpyramid

H2

Cl2 H

2– Bent sp3 Tetrahedral

F4, TeCl

4Irregrular sp3d Trigonaltetrahedron bipyramidT-shaped sp3d Trigonal

bipyramid

eF2, Cl

2Linear sp3d Trigonal

bipyramid IF

5, BrF

5Square sp3d2 Octahedralpyramid

, Cl4

– Square sp3d2 Octahedralplaner

F Shapes of Molecules and Ions and p-p π BondsExamples Shape Number Number Hybrid Hybrid Electron

of of orbital type pairσ lone number arrangementbonds pairs

O = C = O, Linear 2 0 2 sp LinearH – C ≡ NHCO

3–,NO

3– Triangular 3 0 3 sp2 Trigonal

planarO

3,NO

2Bent 2 1 3 sp2 Trigonal

F The dipole moments of some typical substances are given below :Molecule µ Molecules µH

2,N

2, Cl

2, Br

20 CH

4 , C

2H

6, C

2H

40

CO2, CS

2, SnCl

40 C

2H

2, CCl

4, C

6H

60

HF 1.90HCl 1.03 CH

3Cl 1.86

HBr 0.78 CH3Br 1.78

HI 0.38 C2H

5NH

21.3

H2O 1.84 CH

3COOH 1.4

H2S 1.10 p-dichlorobenzene 0

CO 1.10 m-dichlorobenzene 1.48NH

31.46 o-dichlorobenzene 2.25

SO2

1.60PH

30.56

H2O

22.1



F Comparison of Dipole Moment, µ with (Xx – X

H) for Hydrogen Halides is given as under :

H – F H – Cl H – Br H – Iµ 1.98 1.03 0.79 0.38

(Xx – X

H) 1.9 0.9 0.7 0.4

On this basis the percent ionic character of some typical bonds are given below :

C – H N – H O – H F – H4% 19% 39% 60%C – F C – Cl C – Br C – I

43% 11% 3% 1%

F Successive ionization energies of gaseous atoms (KJ mol–1)Element Electronic config. First Second ThirdH 1s1 1312.0

He 1s2 2378.0 5255Li 1s2 2s1 518.0 7314 11820

Be 1s2 2s2 899.1 1757 14810B 1s22s22p1 800.4 1460 3644C 1s22s22p2 1086.6 2351 4560

N 1s22s22p3 1402.9 2858 4577O 1s22s22p4 1315.9 3389 5301

F Bond-Dissociation EnergiesMolecule D (X – X) Molecule D (X – X)

kj mol–1 kJ mol–1

CO 1071.7 CeF 253.3

N2

940.5 Se2

270.4NO 627.0 Cl

2242.0

C2

601.9 BrF 234.0

HF 562.6 BrCl 218.6O

2494.5 ICl 210.3

P2

488.6 Br2

192.7H

2435.5 IBr 177.6

HCl 430.5 F2

158.0

OH 424.0 I2

150.8HBr 365.3 Li

2110.3

HS 335.3 Na2

75.2S

2489.6 K

251.0

As2

376.2 Rb2

48.5

B2

288.4 Cs2

44.7



F Average single bond energies :B o n d Energy B o n d Energy

kJ mol–1 kJ mol–1

C – F485 P – Br 267H – O 464 S – S 263C – H 414 As – H 255N – H 388 Cl – F 255S – H 368 C – I 338C – C 347 S – Br 213C – Cl 326 P – I 213P – H 318 Cl – O 209P – Cl 318 N – Cl 200C – N 293 P – P 172S – Cl 276 As – As 167

N – N 159C – Br 276 Sb – Sb 142

F Average multiple bond energies :B o n d Energy kJ mol–1

N ≡ N 940C ≡ N 890C ≡ C 811C = O 748C = C 619C = N 614C = S 476N = N 418

F Contributions to the total vander Waals bonding :Molecule Dipole Dipole-induced Dispersion TotalB .P .

dipole dipole KAr 0.000 0.000 8.48 8.48 76C O 0.000 0.000 8.73 8.73 81H C l 13.30 1.00 16.80 21.10 188NH

313.28 1.54 15.71 29.53 239.6

H2O 36.33 1.92 8.98 47.23 373.7

F Influence of H-bonding on the properties of compoundsProperty Behaviour of H-bonded compounds

relative to a non-H bonded oneMolar volume L o w e rDensity HigherA – H.... B bond length ShorterThermal conductivity Higher



Viscosity HigherDiffusion (self) in liquid SlowerSurface tension HigherInfrared vibration ShiftedNMR (chemical shift) ShiftedVapour pressure LowerMelting point HigherBoiling point Higher

F Numerical values of quantities for some Compounds :U ∆H

f∆H

sub∆H

dissI E

A

NaCl –769 – 409 108 121 493 363K C l – 702 – 434 83 121 418 354M g O – 3929 – 610 150 246 2178 745C a O – 3519 – 635 196 246 1726 716M g S – 3252 – 343 150 280 2178 301C a S – 3013 – 476 196 280 1726 335

F Lattice Energies of some alkali metal halidesCrystal Experimental Calculated lattice energy

lattice energy, – U (kj/mole)– U (kJ/mole)

N a F 907.9 907.9NaCl 769.9 762.5N a B r 736.4 723.8N a l 690.4 677.8K F 803.3 803.3K C l 702.9 694.5K B r 674.2 667.3K I 674.6 665.2

F Heavy water reacts with a number of hydrogen compounds in which hydrogenatoms are exchanged with deuterium partially or completely. Some of these exchangereactions are tabulated below :Hydrogen compound Observation1. Benzene, C

6H

6No exchange

2. Glucose and Sucrose Hydrogen of –OH groups exchanged3. Acetone, CH

3COCH

3Exchanges all hydrogen in alkaline medium

4. Hydrogen peroxide, H2O

2Exchanges both hydrogen atoms to give D

2O

2

5. Ammonium salts, NH4

+ Exchanges all hydrogen atoms to give ND4

+

6. Hexamminecobalt (III) ion, Exchanges all hydrogen atoms[Co(NH

3)

6] 3+

7. Acetate ion, CH3COO– No exchange

8. Acetylene, C2H

2Exchanges both the hydrogen atoms in alkalinemedium showing acidic nature of C – H.



F Physical properties of some solvents are given below :

Solvent Melting Boiling Dielectric Electrolytic conductivity

point, K point, K constant (siemens per cm or S cm–)

H2O 273 373 81.7 at 291 K 4 × 10–3 at 291 K

NH3

195 240 23 at 240 K 5 × 10–11 at 240 K

HF 190 292.5 84 at 273 K 1 × 10–6 at 273 K

H C l 162 189 9.28 at 178 K 3 × 10–3 at 193 K

H B r 187 206 7.0 at 188 K 1 × 10–6 at 189 K

H I 222.2 237.5 3.39 at 223 K 8 × 10–9 at 228 K

H2S O

4283.4 ~ 6 7 5 110 ± 10 at 293 K 1 × 10–2 at 298 K

(dec.)

SO2

197.5 263 15.4 at 273 K 3.4 × 10–3 at 263 K

N3O

4260.7 294.7 2.42 at 273 K 2 × 10–13 at 290 K

F Acid - Base Chart

(Arranged in the order of the decreasing acid strength)

Acid Conjugate Base

Name Formula Formula Name

Perchloric acid HClO4

ClO4– Perchlorate ion

Sulphuric acid H2SO

4HSO

4– Hydrogen sulphate ion

Hydrogen chloride HCl Cl– Chloride ion

Nitric acid HNO3

NO3– Nitrate ion

Hydronium ion H3O + H

2O Water

Hydrogen sulphate ion H S O4– SO

42– Sulphate ion

Phosphoric acid H3PO

4H

2PO

4– Dihydrogen phosphate ion

Acetic acid CH3COOH CH

3COO – Acetate ion

Carbonic acid H2CO

3HCO

3– Hydrogen carbonate ion

Hydrogen sulphide H3S HS – Hydrosuphide ion

Ammonium ion NH4

+ NH3

Ammonia

Hydrogen cyanide H C N CN – Cyanide ion

Phenol C6H

5OH C

6H

5O – Phenoxide ion

Water H2O OH – Hydroxide on

Ethanol C2H

5OH C

2H

5O – Ethoxide ion

Ammonia NH3

NH2– Amide ion

Methylamine CH3NH

3CH

3NH

2– Methylamide ion

Hydrogen H2

H – Hydride ion

Methane CH4

CH3

– Methide ion



F Classification of acids are given below :

Hard acid Borderline acid Soft acids

H+, Li+, Na+, K+, Fe2+, Co2+, Ni2+, Cu2+, Co(CN)32–, Pd2+, Pt2+, Pt4+

(Rb+, Cs+) Zn2+

Be2+, Be(CH 3)2, Mg 2+, Rh 3, Ir3+, Ru2+, Cu+, A g+, Au+, Cd2+, Hg22+

Ca2+, Sr2+, Ba2+ Hg2+, CH3Hg+

B(CH3)

3, GaH

2BH

3, Ga(CH

2)

3, GaCl

3,

Sc3+, La3+, Ce4+, Gd3+ GaBr3, GaI

3, Tl+, Tl(CH

3)

3

Lu3+, Th4+, U4+, UO22+, R

3C+, C

6H

5+, Sn2+, Pb2+

Pu4+ CH2 carbenes

Ti4+, Zr4+, Hf4+, VO2+ NO+, S b3+, Bi3+

Cr3+, Cr6+, MoO3+, WO4+, π-acceptors : trinitroben-

Mn2+, Mn7+, Fe3+, Co3+ SO2

zene, chloranil, quinones

tetracyanoethylene, etc.

BF2, BCl

3, B(OR)

3, Al3+,

Al(CH3)

2, AlCl

3.AlH

3HO+, RO+, Rs+, RSe+,

Ga 3+, In3+ Te4+, RTe+

CO2, RCO+, NC+, S i4+ Br

2, Br+, I

2, I+, ICN, etc.

Sn4+, CH3Sn3+, (CH

3)

2Sn2+ Br

2, Br+, I

2, I+, ICN,

etc.

N3+, RPO6+, ROPO

2+, As2+ O, Cl, Br, I, N RO –, RO

2

SO3, RSO

2+, ROSO

2+ Mº (metal atoms) and bulk

metals

Cl3+, Cl7+, I5+, I7+

HX (hydrogen-bonding)

molecules)

F Classification of bases are given below :

Hard bases Borderline bases Soft bases

NH3, RNH

2, N

2H

4C

6H

5NH

2, C

5H

5N , N

3– H –

N2

H2O–, OH –, O2–, ROH, R–, C

3H

4, C

5H

4, CN–

RO–, R2O NO

2–, SO

32– RNC, CO

CH3COO–, CO

32–, NO

3– Br – SCN–, R

3P, (RO)

3P , R

3As

PO43–, SO

42–, ClO

4– R

3S, RSH, RS –, S

2O

32–

F–, (Cl–) I–

VISION 2000 122PHYSICS


SOLID STATE

F Seven systems of crystal structure are given as under :

System Characteristics Examples

1. Cubic α = β = γ = 90° NaCl, KAl (SO4)

2. 12H

2O,

and a = b = c diamond

2. Tetragonal α = β = γ = 90° K4Fe(CN)

6, white tin,

and a = b ≠ c NiSO4

3. Orthorhombic α = β = γ = 90° KNO3, MgSO

4, 7H

2O

or Rhombic and a = b ≠ c Rhombic sulphur

4. Triclinic α ≠ β = γ ≠ 90° CuSO4.5H

2O,

and a ≠ b ≠ c K2Cr

2O

7

5. Monoclinic α = γ = 90° ; β ≠ 90° Na2SO

4. 10H

2O, NaHCO

3

and a ≠ b ≠ c FeSO4. 7H

2O

Monoclinic sulphur

6. Trigonal or α = β = γ ≠ 90° Calcite, KMnO4

Rhombohedral and a = b = c and NaNO3

7. Hexagonal α = β = 90° γ = 120° Graphite, quartz

and a = b ≠ c and ice

F Radius ratio and coordination number of some compounds are given below :

Coordination Geometry Limiting radius Possible

number ratio lattice structure

rr

+

–

4 Tetrahedral 0.414 Wurtzite, Since blende

6 Octahedral 0.732 NaCl, rutile

8 Cubic CsCl, fluorite



F Types of solid



COORDINATION COMPOUNDS

F Lattice energy is the amount of energy released when one mole of a crystal is formedfrom the constituent ions present in the gaseous state.

F The geometories of some coordination compounds are given as under :

Coordination compound Hybridised orbitals Molecular geometry

[Ag(NH3)

2]+, [Ag(CN)

2] – s p Linear

[Hgl3] – s p 2 Trigonal planer

[Ni(CO)4], [Zn(NH

3)

4] 2+, [Ni(CN)

4]4– s p 3 Tetrahedral

[Pt(NH3)

4]2+, [Ni(CN)

2]2– dsp 2 Square planer

Cis - [Pt (NH3)

2Cl

2]

[Fe(CO)5] dsp 3 Trigonal bipyramidal

[SbF5]2– s p 3d Square pyramidal

[Co(NH3)

6] 2+ d2s p 3 Octahedral

[CoF6]3– sp 3d 2 Octahedral

F The geometory of [Cu(NH3)

4]2+ is square planer and Cu is in sp 2d hybridization state.

F The strength of ligands increases in the order :

I– < Br– < Cl– < F– < C2O

42– = H

2O < Py = NH

3 < en < NO

2– < CN– < CO

F 18-electron rule. A complex compound in which the central metal atom appears tohave acquired the configuration of an inert gas by the transference or by sharing ofelectrons tends to be more stable. This is called 18-electron rule or inert gas rule.

F More stable coordinate compounds are formed by

(i) Smaller central metal ion

(ii) More strong ligands

(iii) Chelated ligands

F Fixing of negative in photography. After the image has been developed, it is necessaryto fix the film which is done by placing it in hypo solution (Na

2S

2O

3) which will

dissolve the undecomposed AgBr on the film by forming a soluble complex.

AgBr + 2Na2S

2O

3 → Na

3 [Ag(S

2O

3)

2] + NaBr

Sodium argen to

thiosulphate



F Bonding ligands and the number of electrons donated by them is given as under :Number of elements Examples

2 ethylene3 allyl4 cyclobutadiene5 cyclopentadienyl6 benzene, cycloheptatriene7 cycloheptatrienyl8 cyclooctatetraene

F EAN of a few metals in some complexes are given below :Complex Number of Number of

electrons in electron pairs E A NMn + from ligands

[CO(NH3)

6] 3+ 27 – 3 6 36

[Pt(NH3)

6] 4+ 78 – 4 6 86

[Fe(CN)6]4– 26 – 2 6 36

Fe (CO)5

26 – 0 5 36Cr(CO)

624 – 0 6 36

Ni(CO)4

28 – 0 4 36[Ni(NH

3)

6] 2+ 28 – 2 6 38

[Ni(CN)4]2– 28 – 2 4 34

[Cr(NH3)

6] 3+ 24 – 3 6 33

F Molar conductivities of coordination compounds at a concentration of 0.001 M aregiven below :

Empirical formula Conductivity Werner FormationNonelectrolytes

PtCl4.2NH

33.52* [Pt(NH

3)

2Cl

4] (trans)

PtCl4.2NH

36.99* [Pt(NH

3)

2Cl

4] (cis)

1 : 1 Electrolytes (two ions)NaCl 123.7PtCl

4.3NH

396.8 [Pt(NH

3)

3Cl]Cl

3

PtCl4.NH

3.KCl 106.8 K[Pt(NH

3)Cl

5]

1 : 2 and 2 : 1 Electrolytes (three ions)CaCl

2260.8

CoCl35NH

3261.3 [Co(NH

3)

5Cl]Cl

2

CrCl3.5NH

3160.2 [Cr(NH

3)

5Cl]Cl

2

PtCl4.2KCl 256.8 K

2[PtCl

6]

1 : 3 and 3 : 1 Electrolytes (four Ions)LaCl

3393.5

CoCl3.6NH

3431.6 [Co(NH

3)

6]Cl

3

CrCl3.6NH

3441.7 [Cr(NH

3)

6]Cl

3

PtCl4.5NH

3404 [Pt(NH

3)

5Cl]Cl

3

1 : 4 Electrolyte (five ions)PtCl

4.6NH

3522.9 [Pt(NH

3)

6]Cl

4



ATOMIC STRUCTURE

F Quantum Numbers of Electrons in an Atom

Symbol Name Allowed values Information obtained about

n Principal 1, 2, 3, 4 ....n Size and energy associated

with the orbital.

l Azimuthal 0,1, 2, .....n –1 Shape of the orbital

m Magnetic –l, – (l – 1), ...

–1,0, + 1,...(l – 1), + l orientation of orbital

s Spin+12

, −12

Spin of electron



NUCLEAR CHEMISTRY

F Types of nuclei and number of isotopes are given as under :

Constitution of nucleus Number of Abundance

stable percentage in

Neutrons Protons isotopes earth's crust

Even Even 162 87.4

E v e n O d d 52 10.8

O d d E v e n 56 1.8

O d d E v e n 4 0.0007

F Radioactive series are given below :

Uranium Series Thorium Series Actinium Series

(4n + 2 series) (4n series) (4n + 3 series)

Radio Half-life Radio Half-life Radio Half-life

isotope isotope isotope

92U 238 1.45 × 102 years

90Th232 1.39 × 1010 years

92U 235 7.07 × 104 years

– α – α – α

90Th234 24.5 days

88Ra228 6.7 years

90Th231 24.6 hr

– β – β – β

91Pa234 1.14 min

89Ac228 6.13 hr years

91Po231 3.2 × 104

– β – β – α

92U234 2.67 × 105 years

90Th228 1.90 years

89Ac227 21.7 years

– α – α – α – β

90Th230 8.3 × 106 years

86Ra220 3.64 days

87Fr223

90Th227 Th days

Fr18 921

.min

– α – α – β – α

88Ra226 1.62 × 103 years

86Rn220 54.4

88Ra223

88Ra223 11.2 days

– α – α – α

86Rn222 3.82 days

84Po216 0.16 sec

86Rn219 3.92 s

– β ↓ – α

– α

84Po218 3.05 min

85At216

82Pb 212 Pb 10.6 hr

84Po215 1.82 × 10–2 g



– β – α – α – β – α

85At218

62Pb214 Pb

At s26 82

. min83

Bi212 83

Bi212 60.5 s82

Pb 212 3.61 min

– α – β – α – β – β

83Bi214

83Bi214 19.7 min

81Ti208

84Po212 Po 3 × 10–7

83Bi211 2.16 min

– α – β – β – α – α – β

81Ti216

84Po214 Po 1 5 10 4.

sec× − Stable

81TI260

84Po211 Po

Ti2 104 67

1× − sec. min

– β – α TI 2.32 min β – – α

82Ra210

62Ra210 22 years

82Pb207

82Pb207 Stable

– β

83Bi210 4.85 days

– β Po 138.3 days

84PO210 Tl 14.5 min

– α

82Pb206 Stable



METALLURGY

F Liquation is a process in which metals with low melting points like Bi, Sn, Hg, Pbetc. are concentrated and purified.

F Standard electrode potentials and extraction of metals are given below :Electrode Standard Main occurrence Main Method Equation for extractionprocess electrode of extraction

Eº potential

(volts)

Li+, Li –3.05 Spodumene , Electrolysis of fusedLiAl(SiO

3)

2LiCl with KCl added to it

K+, K –2.93 Carnallite, Electrolysis of fusedKCl.MgCl

2.6H

2O KCl with CaCl

2 added to it

Ba2+, Ba –2.90 Witherite, BaCO3; Electrolysis of fused

Barytes; BaSO4

BaCl2

Sr2+, Sr –2.89 Strontianite, SrCO3; Electrolysis of used

Celestine, SrSO4; SrCl

2

Ca2+, Ca –2.87 Limestone, CaCO3

Electrolysis of fused Electrolytic reductionGypsum, CaSO

4; CaCl

2 and CaF

2 mixture in each case

Na+, Na –2.71 Rock salt, NaCl; Electrolysis of fused Mn+ + ne– → MChile saltpetre, NaCl with CaCl

2 added to it

NaNO3

Mg2+, Mg –2.37 Carnallite, Electrolysis of fusedKCl.MgCl

26H

2O MgCl

2 with KCl

Magnesite, MgCO3

added to it

Be2+, Be –1.70 Beryl, Electrolysis of fused3BeO.Al

2O.6SiO

2BeF

2 with NaF added to it

Al3+, Al –1.67 Bauxite, Al2O

3.2H

2O; Electrolysis of Al

2O

3 in

Silicate rocks molten Na3AlF

6

Mn2+, Mn –1.18 Pyrolusite, MnO2; Reduction of oxide 3Mn

3O

4 + 8Al → 9Mn + 4Al

2O

3

Hausmannite , With Al or CMn

3O

4

Ti 4+, Ti –0.95 Illmenite, TiO2.FeO; Reduction of TiCl

4 with TiCl

4 + 2Mg→Ti + 2MgCl

2

Rutile, TiO2

Mg or Na

Zn2+, Zn –0.76 Zinc blende, ZnS; Reduction of ZnO with ZnO + C → Zn + CO

Calamine, ZnCO3

C or electrolysis of ZnSO4

Cr3+, Cr –0.74 Chromite, Reduction of Cr2O

3Cr

2O

3 + 2Al →2Cr + Al

2O

3

FeO.Cr2O

3with Al

Fe3+, Fe –0.41 Magnetite, Fe2O

4Reduction of oxides Fe

2O

3+3CO→ 2Fe + 3CO

2

Haematite, Fe2O

4 with CO

Co2+, Co –0.28 Smaltite, CoAs2

Reduction of Co3O

4 3Co

3O

4+8Al→9Co+4Al

2O

2

With Al



Ni 2+, Ni –0.25 Millerite, Nis Reduction of NiO with NiO + 5CO→Ni(CO)4+CO

2

C O Ni(CO)4 → Ni + 4CO

Sn 2+, Sn –0.14 Cassiterite, SnO2

Reduction of SnO2

SnO2 + 2C → Sn + 2CO

With C

Pb2+, Pb –0.13 Galena, PbS Reduction of PbO PbO + C → Pb + CO

With CBi 2+, Bi +0.32 Bismuth glance, Reduction of Bi

2O

2Bi

2O

3 + 3C → Bi + 3CO

Bi2S

2 ; With C

Bismuthite, Bi2O

3

Cu2+, Cu +0.34 Copper pyrites, Partial oxidation of 2Cu2O + Cu

2S → 6Cu + SO

2

CuFeS2 ; sulphide ore

Cuprite, Cu2O

Ag+, Ag +0.80 Argentite, Ag2S ; Special methods Ag

2S+4NaCN→2NaAg(CN)

2+Na

2S

occurs as metal involving use of 2NaAg(CN)2 + Zn → 2Ag + NaZn(CN)

4

sodium cyanide

Hg2+, Hg +0.85 Cinnabar, HgS Direct reduction of HgS HgS + O2 → Hg + SO

2

Pt2+, Pt +1.20 Occurs as metal ; Thermal decomposition (NH4)

2PtCl

6→Pt+2NH

4Cl+2Cl

2

Sperrylite, PtAs2

of (NH4)

2PtCl

6

Au2+, Au +1.50 Occurs as metal Special methods involving Similar to that for silver

use of sodium cyanide 2NaAu(CN)2 + Zn →

2Au + Na2Zn(CN)

4



QUALITATIVE ANALYSIS

F NH4OH reacts with Fe3+, Cr3+ and Al3+ salts to precipitate their hydroxides.

FeCl3 + 3NH

4OH → Fe(OH)

3 + 3NH

4Cl

Brown ppt.

AlCl3 + 3NH

4OH → Al(OH)

3 + 3NH

4Cl

White ppt.

CrCl3 + 3NH

4OH → Cr (OH)

3 + 3NH

4Cl

Green ppt.

F Silver chloride gets dissolved in NH3 forming diammine silver (l) chloride

AgCl + 2NH3 → [Ag(NH

3)

2] Cl

(Solid) (Soluble)

F Copper sulphate solution gives a deep blue colour with aqueous ammonia forming Tetra amine cop-per (II) sulphate

CuSO4 + 4NH

4OH → [Cu(NH

3)

3] SO

4 + 4H

2O

(Deep blue colour)

F Rf value (Retention factor) in chromatography is defined as

Rf value = Dis ce through which solute moves

Dis ce through which solvent front movestan

tan

F Ninhydrin test is used to detect amino acids, amino phosphatides an amino sugars.

F Prussian blue is chemically Fe4 [Fe(CN)

6]

3

F Sodium nitroprusside or sodium nitrosopenta cyanoferrate (II) is chemically

Na2 [Fe(NO) (CN)

5]. 2H

2O

F Turnbulls' blue. When ferricyanide ion [Fe(CN)6]3– is added to an aqueous solution

of iron (II) salt, gives an intense blue precipitate of Turnbull's blue

K3 [Fe(CN)

6] + FeCl

2 → 2KCl + K Fe [Fe(CN)

6]

(Turnbull's blue)

F Nessler's reagent is prepared by mixing an alkaline solution of HgI2 with KI.

Hgl2 + 2KI → K

2 [HgI

4]

(Nessler's reagent)

Nesler's reagent gives a brown precipitate of Million's base H2N.HgO.Hgl when treated

with NH3

132 CHEMISTRY VISION 2000

INORGANIC CHEMISTRY IIT JEE

SOME IMPORTANT PROCESSES

Bosch process Hydrogen

Castner process Manufacture of Na

Down process Manufacture of Na

Nelson cell Manufacture of NaOH

Caster - Kellner cell Manufacture of NaOH

Solvay process or Manufacture of Na2CO

3 and

Ammonia soda process (Solvay process) NaHCO3, Na

2CO

3

Leblanc process Manufacture of K2CO

3

Frecht (magnesia) process Manufacture of K2CO

3

Mac Arthur Forrest process Manufacture of Ag

(Cyanide process)

Parke's process Manufacture of Ag

Pattinson's process Manufacture of Ag

Cupellation process Purification of Ag

Baeyer's process Manufacture of Al

Serpeck's process Manufacture of Al

Hoop's process Purification of Al

Goldschmidt process Thermite welding



Carter process Manufacture of basic lead carbonate(White lead)

Haber's process Synthesis of NH3

Brikeland - Eyde process Synthesis of NO, HNO3

Ostwald process Synthesis of NO, HNO3

Deacon's process Manufacture of Cl2

Lead chamber process Manufacture of H2SO

4

Contact process Manufacture of H2SO

4

L.D. process Manufacture of steel

Dow's process Manufacture of phenol

Gossage process Manufacture of NaOH

Lane's process Manufacture of H2.



SOME IMPORTANT FACTS

Element which constitutes 90% of the mass of sun : Hydrogen

Most abundant element in the universe : Hydrogen.

Three most abundant elements in the earth's crust : O, Si, Al

Most abundant metals : Al followed by Fe

Element stored under water : Phosphorus

Element stored under kerosine (liquid paraffin) : Na, K, Rb, Cs

Element which sublimes on heating : Iodine

Lightest metal : Lithium

Smallest atomic size : Hydrogen.

Largest atomic size : Caesium

Higest electronegativity : Fluorine

Lowest electronegativity : Caesium

Highest ionization potential : Helum.

Lowest ionization potential : Caesium.

Highest electron affinity : Chlorine

Lowest electron affinity : Noble gases (zero.)

Least electropositive element : Fluorine



Metal with lowest melting point : Mercury

Element with lowest m.p. and b.p. : Helium.

Metal with highest m.p. and b.p. : Tungsten

Non metal with highest m.p. and b.p. : Diamond

Most reactive gaseous element : Fluorine.

Most reactive liquid element (metal) : Caesium.

Most stable element (t1/2

= 2 x 10 21 years) : Tellurium.

Largest anion : Astatide ion (At –)

Smallest anion : F–

Total number of gaseous elements In the periodic table. :

11 (H2, N

2, O

2, F

2, Cl

2 and 6 noble gases)

Total number of liquid elements in the periodic table : 5 (Ga, Br, Cs, Hg and Fr)

Total number of solid elements in the periodic table : 89.

Total number of radioactive elements in the periodic table : 25

Largest group in the periodic table : III B

Liquid radioactive element : Francium.

First man made element : Technetium (At. No. = 43).

Votatile d-block elements : Zn, Cd and Hg.

Rarest element in the earth's crust : Astatine



Most poisonous metal : Plutonium.

The only liquid non-metal : Bromine

Heaviest naturally occurring element : U238

Best conductor among non-metals : Graphite.

Least electrical conductor : Lead (metal), S (non-metal)

Oldest known organic acid : CH3COOH

First compound synthesised from its elements : CH3COOH

Father of chemistry : Lavoisier.

Recipient of first nobel prize in chemistry : Vant Hoff

Element having maximum number of natural isotopes (10) : Tin

Some polymorphic elements : O, S, P.

Some isomorphous substances : FeSO4.7H

2O, MgSO

4, 7H

2O, ZnSO

4.7H

2O.

Some substances which effloresce : Na2CO

3.10H

2O, (Washing soda), Na

2SO

4.10H

2O

(Glauber's salt), MgSO4.7H

2O (Epsom salt), Na

2S

2O

3.5H

2O (Hypo), FeSO

4.7H

2O,

(Green vitriol). (Mohr's salt, FeSO4. (NH

4)

2SO

4.6H

2O does not effloresce).

Strongest oxidising agent : Anode

Strongest reducing agent : Cathode

Some oxidising agents : H2O

2, SO

3, SO

2, Cl

2, H

2SO

4, HNO

3, O

3, F

2, KMnO

4,

K2Cr

2O

7

Some reducing agents : SO2, H

2S, H

2SO

3, CO, SnCl

2, H

2 etc.



Some bleaching agents : SO2, H

2O

2, Cl

2, bleaching powder.

(a) SO2 bleaches temporarily, bleaching action is due to reducing property of SO

2.

(b) Cl2 bleaches permanently, bleaching action is due to oxidising property of chlorine.

(c) Dry bleacher : H2O

2.

Lightest element (Lightest gas) : Hydrogen (H2)

Best conductor of heat and electircity : Ag followed by Cu, Au, Al

Most commonly used metal : Fe followed by Cu.

Poor conductor of heat and bad conductor of electricity : Sulphur

Coinage metals : Cu, Ag, Au.

Compound used to disperse mobs (tear gas) : Phenacyl chloride, C6H

5COCH

2Cl.

Substances used as war gases : Phosgene or carbonyl chloride (COCl2), Mustard gas

Lewisite.



SOME REAGENTS OR MIXTURES

1. Schweiter reagent : Tetramminecopper (II) sulphate - used for dissolving cellulose inthe manufacture of artificial silk.

2. Fehl ing solut ion : Copper sulphate + sod. pot. tartarate (Rochelle salt) + NaOH -used for detecting an aldehydic group.

3. Tollen's reagent : AgNO3 solution + NaOH solution + NH

4OH - used for detecting

an aldehydic group.

4. Benedict solution : Alkaline solution of cupric ion complexed with citrate ions - usedfor detecting - CHO group.

5. Schi f f ' s r eagent : Dilute solution of rosaniline hydrochloride in water whose redcolour has been discharged by passing SO

2 - used for detecting - CHO group.

6. Bordeaux mixture : CuSO4 solution + lime - used to kill moulds and fungi on wines.

7. Soda bleach : A mixture of Na2O

2 and dil. HCl - used for bleaching of delicate fibres

like wool, silk, etc.

8. Soda l ime : A mixture of Ca(OH)2 + NaOH - used as an absorbent for a number of

gases, and in decarboxylation of sodium salts of fatty acids.

9. Fusion mixture : A mixture of Na2CO

3 + K

2CO

3 - used as laboratory reagent.

10. Lithopone : A mixture of ZnS + BaSO4 - used as white paint.

11. Sublimed white lead : PbSO4 + PbO + ZnO - used as white paint.

12. Carbogen : A mixture of O2 and 5 - 10% CO

2 - used for artificial respiration.

13. Nessler 's reagent : K2HgI

4 - used for detecting NH

4+ ions.

14. Nitrol ium : Calcium cyanamide + graphite - used as fertilizer.

15. Superphosphate : Calcium dihydrogen phosphate + CaSO4 - used as fertilizer.

16. Thomas slag : Tricalcium phosphate + cal. silicate used as - fertilizer.

17. Baeyer's reagent : Cold 1% alkaline KMnO4 solution - used for detecting olefinic and

acetylenic linkages.



18. Molisch reagent : α - Naphthol dissolved in alcohol is used for detecting carbohydrates.

19. Lindlar catalyst : Palladised charcoal deactivated with sulphur compounds - partialhydrogenation of triple bond to double bond.

20. Milk of magnesia : Suspension of Mg(OH)2 in water - used as antacid.

21. Gun powder : A mixture of S, charcoal and KNO3 - used as explosive.

22. Purp l e o f ca s s iu s : Colloidal particles of gold absorbed by colloidal precipitate ofstannic acid - used for colouring glass (rubby red) and pottery.

23. Lucas reagent : A mixture of conc. HCl and anhy. ZnCl2 - used for distinguishing

three types of alcohols.

24. Rectified spirit : 93 - 95% ethanol.

25. Methylated spiriti : (Denatured alcohol). Rectified spirit + CH3OH, pyridine, acetone

etc.

26. Power alcohol : 4 parts petrol + 1 part alcohol.

27. Brady's reagent : 2, 4-Dinitrophenylhydrazine.

28. Lemieux reagent : Aqueous solution of sodium periodate + a trace of KMnO4 - used

for detection and location of a double bond in organic compounds.

29. Sanger ' s r eagent : 2, 4-Dinitrofluorobenzene, used for amino end analysis of apolypeptides, i.e. for detection of amino acid sequence in polypeptides.

30. Tildon's reagent : It is nitrosyl chloride, used for detecting the presence of olefiniclinkage.

31. Hofmann reagent : It is diethyl oxalate, used for the separation of a mixture of 1º,2º and 3º amines.

32. Hinsberg reagent : It is benzenesulphonyl chloride, used for separating a mixture of1º, 2º and 3º amines.

33. Malaparade reagent : It is periodic acid and used for cleaving vicinal glycols givingaldehydes, ketones or their mixtures.

34. Ninhydrin reagent : It is triketohydridene hydrate : used for detecting the presenceof amino acids and proteins with which it gives violet, pink or red colour.



IMPORTANT PHYSICAL PROPERTIES OF SOME GASES

1. Hydrogen, H2 : Colourless, odourless, tasteless, lightest gas, sparingly soluble in water, combustibel

and burns in air or oxygen with nearly invisible pale blue flame, neutral, can be liquefied and solidi-fied.

2. Carbon monoxide, CO : Colourless, faint odour, tasteless, as heavy as air, very sparingly soluble inwater, burns in air with blue flame, neutral, poisonous.

3. Carbon dioxide, CO2 : Colourless, faint, pungent smell, heavier than air (1.5 times) and can be

poured downward like water, fairly soluble in water. Acidic, non-poisonous, can be liquefied and so-lidified.

4. Nitrogen, N2 : Colourless, odourless, tasteless, slightly lighter than air, slightly soluble in water, no-

poisonous, can be liquefied.

5. Nitrogen oxide, N2O (laughing gas) : Colourless, faint pungent smell, fairly soluble in cold water

but not in hot water, heavier than air, and poisonous.

6. Nitric oxide, NO : Colourless, slightly heavier than air, sparingly soluble in water, paramagnetic,neutral, can be liquefied with great difficulty.

7. Dinitrogen trioxide, Nitrous anhydride : N2O

3 : Reddish brown gas which on cooling gives a deep

blue liquid.

8. Nitrogen dioxide, NO2 : Reddish brown gas, paramagnetic.

9. Nitrogen tetroxide, N2O

4 : Colourless solid (exists below 10ºC), diamagnetic.

10. Ammonia, NH3 : Colourless, characteristic pungent smell, lighter than air, extremely soluble in

water, brings tears in eyes, basic in nature, can be liquefied and solidified.

11. Oxygen, O2 : Colourless, odourless, tasteless, slightly heavier than air, slightly soluble in water, can

be liquefied and solidfied, non-inflammable, paramagnetic.

12. Ozone, O3 : Pale-blue, fishy smell, heavier than air, slightly soluble in water, poisonous due to its

destructive action on tissues, can be liquefied, turns starch iodide paper blue, Hg loses its meniscus incontact with O

3.

13. Hydrogen sulphide, H2S : Colourless, smell of rotten eggs, soluble in water, poisonous.



14. Sulphur dioxide, SO2 : Colourless, pungent and suffocating odour, heavier than air,

soluble in water, poisonous, can be liquefied and solidified.

15. Chlorine, Cl2 : Greenish - yellow, suffocating smell, heavier (2.5 times) than air, fairly soluble in

water, poisonous, can be liquefied.

16. Bromine, Br2 : Reddish brown, heavier than air, highly soluble in water, poisonous, turns starch paper

yellow.

17. Iodine, I2 : Violet, sparingly soluble in water.

18. Hydrogen halides, HX : Colourless, pungent smelling, acidic taste, fairly soluble in water, heavierthan air, can be liquefied.

19. Some important mixture of gases : Water gas (CO + H2) - used for the production of H

2 and as a

fuel. Producer gas (CO + N2 + little CO

2) used as fuel gas.

20. Some gases used in warfare : Phosgene (COCl2), mustard gas (ClC

2H

4 - S - C

2H

4Cl), tear gas

(CCl3.NO

2), lewisite (CHCl = CHAsCl

2).



SOME IMPORTANT COMPOUNDS/MINERALS

Permutit (Zeolite) Na2Al

2SiO

8x H

2O

Calgon Na2P

6O

18

Chile saltpetre NaNO3

Salt cake Na2SO

4 (anhydrous)

Glauber's salt Na2SO

4.10H

2O

Nitre salt NaHSO4

Borax Na2B

4O

7.10H

2O

Soda ash Na2CO

3 (anhydrous)

Pearl ash, Potash K2CO

3

Washing soda Na2CO

3.10H

2O

Crystal carbonate Na2CO

3.H

2O

Baking soda NaHCO3

Sylvine K C l

Carnallite KCl.MgCl2. 6 H

2O

Felspar KAlSi3O

8

Salt petre (Indian salt petre) KNO3

Kainite KCl. MgSO4.3H

2O

Schonite K2SO

4. M g S O

4. 6 H

2O

Sorels' cement (Magnesia cement) MgCl2.5MgOxH

2O



Magnesite MgCO3

Dolomite MgCO3.CaCO

3

Kieserite M g S O4.H

2O

Epsomite (epsom salt) M g S O4. 7 H

2O

Asbestos CaMg3(SiO

3)

4

Talc Mg2(Si

2O

5)

2Mg(OH)

2

Magnesia alba (MgCO3)

x [Mg(OH)

2]

y.H

2O

Lime stone, marble or chalk CaCO3

Gypsum CaSO4. 2 H

2O

Plaster of Paris CaSO4.1/2H

2O

Anhydrite (dead burnt) CaSO4

Dolomite CaCO3.MgCO

3

Fluorspar CaF2

Phosphorite Ca3(PO

4)

2

Quick lime (burnt lime, lime) C a O

Salked lime Ca(OH)2

Soda lime Ca(OH)2 + NaOH

Coinage (Currency) metals Cu, Ag and Au

Copper pyrites CuFeS2 or Cu

2S.Fe

2S

3

Cuprite (Ruby copper) Cu2O



Copper glance Cu2S

Malachite Cu(OH)2.2CuCO

3

Azurite Cu(OH)2.2CuCO

3

Blue vitrol CuSO4.5H

2O

Green vitrol FeSO4. 7 H

2O

Argentite (silver glance) Ag2S

Horn silver (Chlorargyrite) AgCl

Ruby silver (Pyrargyrite) Ag2SbS

3

Argentiferous galena PbS + Ag2S

Lunar caustic AgNO3

Zinc blende ZnS

Calamine ZnCO3

Zincite (Red ZnO) Z n O

Philospher's wool Z n O

Willemite Zn2SiO

4

Bauxi te Al2O

3.2H

2O

Corundum Al2O

3

Diaspore Al2O

3.H

2O

Cryolite Na3AlF

6

Kaolinite Al2O

3.2SiO

2.2H

2O



Mica K2O.3Al

2O

3.6SiO

2.2H

2O

Alums M2SO

2.M

2(SO

4)

3.24H

2O

Alum shale (Pyrites shale) Al2O

3xSiO

2 + FeS

2

Alum stone (Alunite) K2SO

4. Al

2(SO

4)

3.4Al(OH)

3

Cassiterite (Tin stone) SnO2

Galena P b S

Anglesite P b S O4

Cerussite PbCO3

Lanakite P b O . P b S O4

Massote (Litharge) P B O

Laughing gas N2O

Chlorapatite 3Ca3(PO

4)

2.CaCl

2

Apatite (Fluorapatite) 3Ca3(PO

4)

2. C a F

2

Barytes BaSO4

Haematite (Red haematite) Fe2O

3

Limonite (Brown haematite) Fe2O

3. 2 H

2O

Magnetite Fe3O

4

Siderite (Spathic iron ore) FeCO3

Iron pyrites FeS2

Mohr's salt FeSO4. (NH

4)

2SO

4.6H

2O



SOME IMPORTANT COMPOUNDS AND THEIR USES

1. Permutit , ion exchange res ins and calgon : For removing permanent hardness ofH

2O.

2. Heavy water (D2O ) : A moderator in nuclear reactor.

3. Hydrogen peroxide : Bleaching agent, oxidising agent, restoring colour of lead paintingblackened by H

2S, antiseptic, germicide, propellent or fuel in rockets, etc.

4. S o d i u m m e t a l : Preparation of TEL, sodium amalgam, in sodium vapour lamp,heat transfer medium in nuclear reactors, Na – K alloy (liquid at room temperature)is used in high temperature thermometers used for finding temperature above theb.p. of mercury.

5. Sodium peroxide, Na2O

2. Oxidising agent, source of oxygen under the name of

oxone, purification of air, bleaching agent (soda bleach – Na2O

2 + dil. HCl).

6. Sodium hydroxide, NaOH : For mercerizing cotton to make cloth unshrinkable.

7. Sodium carbonate , washing soda Na2CO

3 : In laundries, manufacture of glass,

fusion mixture (Na2CO

3 + K

2CO

3) .

8. Sodium bicarbonate, Baking soda, NaHCO3 : Preparation of baking powder, siedlitz

powder, effervescent drinks and furit salts, in fire extinguishers, as antacid.

9. Sodium sulphate, Glauber 's salt : Na2SO

4.10H

2O. Craft paper, window glass, mild

laxative.

10. Potassium metal : Used in photoelectric cells.

11. Potassium carbonate. K2CO

3 : Soft soap, hard glass, fusion mixture, washing wool.

12. Potassium bicarbonate, KHCO3 : Used in medicine and baking powder.

13. Potassium sulphate : K2SO

4. As fertilizer, in potash alum and glass, as a purgative

in medicine.

14. Magnesium metal : Preparation of Grignard reagent (RMgX) used in organic chemistry,as a fuse in aluminothermic process, as a source of light in photography.

15. Magnesia, MgO : As antacid, as refractory lining, as basic lining, as insulator, rubberfiller, Sorels' cement (MgCl

2. 5MgOxH

2O) used in filling teeth and as a substitute

for tiles.



16. Magnesia alba (MgCO3)

x [Mg(OH)

2]

y ZH

2O : In medicines as an antacid, laxative

and in tooth powders and pastes and in silver polishes.

17. Magnesium carbonate : Refractory material, filler for rubber and paper.

18. Magnesium sulphate : Purgative, fire-proof fabrics, filler in paper.

19. Quick lime, CaO : Bleaching powder, slaked lime, lime colours, cement and calciumcarbide, purification of sugar and coal gas, softening of water, as basic lining.

20. Slaked lime, Ca(OH)2 : Belaching powder, caustic soda and soda lime, white washing,

softening of water.

21. Calcium carbonate, CaCO3 : Used as limestone for the manufacture of lime and as

a flux ; as marble for building purposes and in the production of CO2 ; as chalk in

paints and distempers and in the production of CO2 ; as precipitated chalk in tooth

pastes and powders, in medicines for indigestion.

22. Calcium sulphate, CaSO4 : Plaster of paris, cement, ammonia, black board chalks,

H2SO

4 and ammonium sulphate.

23. Copper meta l : Electrical wires, cables, calorimeters. For electroplasting andelectrotyping, coinage metal, in ornaments and jewellery.

24. Copper sulphate, CuSO4.5H

2O : In Bordeaux mixture, electroplating, electrotyping,

dyeing, calicoprinting, detecting moisture, preparing Fehling solution, as insecticide.

25. Si lver meta l : In coins, ornaments, filling teeth (silver - alloy), medicines, silverplating.

26. Lunar caust ic , AgNO3 : In making inks and hari dyes, silvering of mirros, as a

caustic in surgery. AgX (except AgI) are used in photography.

27. Zinc meta l : In galvinisation, desilverisation of lead, precipitation of Ag and Au*cyanide process), reducing agent (Zn dust).

28. Zinc white, ZnO : As white pigment under the name of zinc white or chinese white,as zinc ointment, as filler in rubber industry, white shoe polish.

29. Zinc sulphide, ZnS : In lithopone, X-ray screens and in luminous paint of the dialsof watches.

30. Alumina, Al2O

3 : As a refractory material, cement (bauxite + lime), abrasive, for

preparing artificial gems, in chromatography.



31. Aluminium chloride, AlCl3 : In Friedel - Craft reaction.

32. A l u m , K2SO

4.Al

2(SO

4)

3.24H

2O : In purification of water, tanning of leather, as

mordant in dyeing, as a styptic to arrest bleeding, for sizing of paper.

33. Carbon monoxide, CO : Production of water gas and producer gas, in extraction ofiron and nickel, reducing agent.

34. Carbon dioxide, CO2 : As a fire extinguisher, refrigerant (as dry ice), for artificial

respiration (as carbogen), manufacture of aerated water, white lead and Na2CO

3

(Solvay process).

35. Tin metal : Tin foil is used for wrapping cigaretters, confectionery and for makingtooth paste tubes.

36. Stannous chloride : Mordant in dyeing (under the name of tin salt), for preparingpurple of cassius, as a reducing agent.

37. Butter of tin (Oxymuriate of tin), SnCl4.5H

2O : Mordant.

38. Pink salt, (NH4)

2SnCl

6 : Mordant.

39. Lithrge, PbO : (Buff coloured crystalline variety). For making lead glass, paints andvarnishes ; in glazing pottery.

40. Massicot, PbO : (yellow powder). When mixed with glycerine, it is used as a cementfor glass and stone.

41. Lead perox ide , PbO2 : In storage batteries, in match industry, oxidising agent in

laboratory.

42. Trilead, Minium, Red lead, Pb3O

4 : In paint, silver mirrors, lead glass (flint glass),

matches and oxidising agent.

43. Basic lead carbonate, White lead, 2PbC O3.Pb(OH)

2 : White paint.

44. Nitrous oxide, Laughing gas, N2O : As propellent gas, anaesthetic.

45. Nitric oxide, NO : Intermediate in HNO3 manufacture, catalyst in lead chamber, in

detection of oxygen.

46. Nitrous acid, HNO2 : Used in preparation of azo dyes.



47. Nitric acid, HNO3 : In making explosives (T.N.T., picric acid, nitroglycerine, dynamite

and gun cotton), fertilizers (ammonium nitrate, calcium nitrate), artificial silk, dyes,drugs, perfumes ; in the purification of silver and gold ; as a solvent for etchingdesigns or names upon copper, brass and bronze articles.

48. Ammonia, NH3 : In making HNO

3, NaHCO

3, (NH

4)

2SO

4 and amm. calcium

sulphate (both fertilizers), NH4NO

3 (explosive), artificial silk ; as a cleaning agent

for removing grease in dry cleaning.

49. Phosphorous : Red P in match industry, white as rat poison.

50. Phosphorus pentoxide, P2O

5 : Dehydrating agent.

51. Calcium ammonium nitrate (CAN) : Nitrogenous fertilizer.

52. Oxygen , O2 : Oxygen + CO

2 o r O

2 + He for artificial respiration ; liquid O

2 +

finely divided C as a substitute of dynamite ; liquid O2 as rocket fuel ; oxy-hydrogen

and oxy-acetylene flames are used for cutting and welding purposes.

53. Ozone, O3 : As sterilising agent for water, for improving the atmosphere of crowded

places, mild bleaching agent, for detecting the position of double bond, for preparingKMnO

4 from K

2MnO

4, artificial silk and synthetic camphor.

54. Sulphur : In match industry and fireworks, vulcanization of rubber, disinfectant forhouses, skin medicines and in preparing sulphur dyes.

55. Hydrogen sulphide, H2S : Reducing agent, laboratory reagent.

56. Sulphur dioxide, SO2 : Bleaching agent, antichlor, solvent (liquid SO

2).

57. Sulphur trioxide, SO3 : Manufacture of H

2SO

4, oleum ; for drying gases.

58. Oi l o f v i t r io l , H2SO

4 : In preparing dyes, fertilizers, detergents, explosives, lead

storage batteries, dehydrating agent, pickling agent.

59. Hypo, Na2S

2O

3.5H

2O : Fixing agent in photography, as an antichlor in volumetric

analysis, in the extraction of Au and Ag from ores.

60. Chlor ine , Cl2 : Bleaching agent, purification of drinking water, as germicide, as

disinfectant in swimming pools, preparation of domestic antiseptic solution (NaOCl),bleaching powder, chlorates, DDT, poisonous gases like COCl

2, tear gas and mustard

gas.

61. Sodium and potassium bromides : Sedatives. AgBr is used in photography.



62. Iodine, I2 and KI : are used in treating goitre ; for increasing production of eggs.

63. Bleaching powder, CaOCl2 : Bleaching agent, sterilising drinking water, for making

woold unshrinkable.

64. Green vitriol (hara kasis) , FeSO4.7H

2O : Preparation of blue-black (writting) ink,

as mordant in dyeing and tanning industries, as insecticide in organic analysis.

65. Ferr ic ox ide , Fe2O

3 : As a red pigment, as a polishing powder in jewellery, as a

catalyst for the oxidation of CO to CO2.

66. 2, 2, 4-Trimethylpentane (iso-octane) : increases the anti-knock quality of petrol(gasoline).

67. Tetraethyl lead (TEL), (C2H

5)

4Pb : Anti-knocking agent.

68. Carbon black : In black paints, printer's ink, as filler in rubber.

69. Ethylene bromide : Increases the efficiency of TEL.

70. Ethylene : General anaesthetic.

71. Acetylene : Illumination of hawker's lamps, artificial ripening of fruits.

72. Westron and Westrosol : Solvent

73. Chloroprene : A Synthetic rubber

74. Acryloni tr i le , CH2 = CHCN : In preparing buna N (synthetic rubber) and orlon

(synthetic fibre).

75. Vinyl acetate : CH2 = CHOCOCH

3. In plastic industry.

76. Viny chloride, CH2 = CHCl : In preparing polyvinyl chloride (PVC).

77. Gammexene, γ-B.H.C. : (γ-benzene hexachloride). Insecticide.

78. Chloroform : Anaesthetic, preparing chloropicrin (insecticide) and chloretone(hypnotic), preservative for anatomical specimens.

79. Iodoform : Antiseptic.



80. Freon -12, CCl2F

2 : As refrigerant and propellent.

81. Carbon te t rachlor ide , CCl4 : Fire extinguisher (pyrene), solvent, anthelmentic

(elimination of hookworms), fumigant.

82. Ethyl a lcohol , C2H

5O : Beverages, solvent, antifreeze for automobile radiators, in

appratuses like spirit levels, powder alcohol.

83. Phenol C6H

5OH : Antiseptic, preparing salol (intestinal antiseptic), aspirin (antipyretic

and antiseptic), picric acid (explosive), phenolphthalein (indicator), bakelite (asynthetic plastic, used in buttons, electric switches, etc.)

84. Ether : General anaesthetic, refrigerant, perfumes, solvent ; for preparing Grignardreagent, in Wurtz reaction.

85. Phenacyl chloride, C6H

5.CO.CH

2Cl : Lachrymator to disperse mobs.

86. Urotropine (Hexamethylene tetramine) : Urinary antiseptic.

87. Formaldehyde : (40% solution is known as formalin). As a preservative for biologicaland anatomical specimens, in preparation of urotropine, bakelite, in silvering ofmirror.

88. Acetaldehyde, CH3CHO : Antiseptic in nose troubles.

89. Acetaldehyde ammonia : A rubber accelerator.

90. Paraldehyde, (CH2O)

n : A hypnotic and sporofic.

91. Metaldehyde, (CH–2

O)3 : Solid fuel in spirit lamp.

92. Acetone : For storing acetylene.

93. Chloretone : Hypnotic and sedative.

94. Formic acid : In tanning for removing lime from hides, as a reducing agent.

95. Acetic anhydride : Acetylating agent ; preparation of dyes, acetate rayon, aspirin.

96. Ethyl acetate : In perfumes, in skin diseases.

97. Aniline : In preparation of dyes and dye intermediates, accelerators, antioxidants,sulphadrugs.

98. Acetanilide : Antipyretic under the name of antifebrin.



Arrange the following as mentioned :

1. Decreasing ionic size Mg2+ , O2- , Na+ , F- (1985)

2. Increasing acidic property ZnO, Na2O

2 , P

2O

5, MgO (1985)

3. Increasing first ionization potential Mg, Al , Si , Na (1985)

4. Increasing bond lenght F2, N

2, Cl

2, O

2(1985)

5. Increasing size Cl-, S2-, Ca2+ , Ar (1986)

6. Increasing acid strength HClO3, HClO

4, HClO

2, HClO (1986)

7. Increasing bond strength HCl, HBr, HF , HI (1986)

8. Increasing oxidation number of iodine I2,HI, HIO

4, ICl (1986)

9. Increasing thermal stability HOCl, HOClO2, HOClO

3, HOClO (1988)

10. Increasing bond enthalpy N2, O

2, F

2, Cl

2(1988)

11. Increasing acidic character CO2, N

2O

5, SiO

2, SO

3(1988)

12. Increasing ionic size N3-. Na+ , F-, O2-, Mg2+ (1991)

13. Increasing basic character MgO, SrO, K2O, NiO, Cs

2O (1991)

14. Increasing extent of hydrolysis CCl4, MgCl

4, AlCl

3, PCl

5, SiCl

4(1991)

15. Increasing strenght of hydrogen bonding ( X .......H - X ) O,S,F,Cl,N (1991)

16. Increasing ionic radii in water Li+, Na+, K+, Rb+, Cs+

17. Increasing molar conductivity in water Li+, Na+, K+, Rb+, Cs+

EXERCISE # 1



18. Increasing reactivity with water Li, Na, K, Rb, Cs

19. Increasing reactivity with hydrogen Li, Na, K, Rb, Cs

20. Increasing melting point Li, Na, K, Rb, Cs

21. Increasing basic nature of hydroxides LiOH, NaOH, KOH, RbOH, CsOH

22. Increasing thermal stability of hydroxides LiOH, NaOH, KOH, RbOH, CsOH

23. Increasing covalent character LiCl, LiBr, LiI

24. Increasing ionic character CaCl2, BeCl

2, MgCl

2, BaCl

2, SrCl

2

25. Increasing solubility BeCO3, MgCO

3, CaCO

3, BaCO

3

26. Increasing solubitily BeF2, MgF

2,CaF

2,BaF

2

27. Increasing solubitily Be (OH)2, Mg(OH)

2, Ca (OH)

2, Ba (OH)

2

28. Increasing basicity Be (OH)2, Mg(OH)

2, Ca (OH)

2, Ba (OH)

2

29. Increasing hydration of ions Be2+ , Mg2+, Ca2+ , Sr2+ , Ba2+

30. Increasing reactivity with water Be , Mg, Ca , Sr , Ba

31. Increasing reactivity towards air Be , Mg, Ca , Sr , Ba

32. Increasing solubility BeSO4, MgSO

4, CaSO

4, SrSO

4, BaSO

4

33. Increasing ionic character BCl3, AlCl

3, GaCl

34. Increasing strengthof Lewis acid BF3, BCl

3, BBr

3

35. Increasing strength of Lewis acid AlCl3, GaCl

3, InCl

3

36. Increasing reducing power GeCl2, SnCl

2, PbCl

2

37. Increasing oxidizing power GeCl4, SnCl

4, PbCl

4



38. Increasing number of hybrid orbitals of C, Si, Sn

39. Increasing basic character NH3,AsH

3, SbH

3, PH

3

40. Increasing thermal stability NH3,AsH

3, SbH

3, PH

3

41. Increasing acidic strength HNO3, H

3PO

4, H

3AsO

4, H

3SbO

4

42. Increasing solubility in water HNO3, H

3PO

4, H

3AsO

4, H

3SbO

4

43. Increasing order of + 5 oxidation state N, P, As , Sb and Bi

44. Increasing extent of hydrolysis NCl3, PCl

3, AsCl

3, SbCl

3, BiCl

3

45. Increasing stability of hydrides H2O, H

2S, H

2Se, H

2Te

46. Increasing poisonous nature H2S, H

2Se, H

2Te, H

2Po

47. Increasing acidic strength of oxoacids H2O, H

2S, H

2Se, H

2Te

48. Increasing strength of oxoacids H2SO

3, H

2SeO

3, H

2TeO

3

49. Increasing stability of oxoacids H2SO

3, H

2SeO

3, H

2TeO

3

50. Increasing strength of oxoacids H2SO

4, H

2SeO

4, H

2TeO

4

51. Increasing stability of oxoacids H2SO

4, H

2SeO

4, H

2TeO

4

52. Increasing electron affinity F, Cl, Br, I

53. Increasing reducing power HF, HCl, HBr, HI

54. Increasing affinity for hydrogen F2, Cl

2, Br

2, I

2

55. Increasing acidity HF, HCl , HBr , HI

56. Increasing melting point HF, HCl , HBr , HI

57. Increasing boiling point HF, HCl , HBr , HI



58. Increasing stability HFO3, HClO

3, HBrO

3, HIO

3

59. Increasing covalent character TiCl2, TiCl

3, TiCl

4

60. Increasing magnetic moment Ti3+ , Ni2+ , Cr2+, Co2+ , Zn2+

61. Increasing ionic character VCl2, VCl

3, VCl

4

62. Increasing electropositivity Fe, Na, Cu, Li

63. Increasing density Fe, Pb, Al, Au

64. Increasing basic characteristics Li2O, BeO, B

2O

3, CO

2

65. Increasing electronegativity As, P, S, Cl

66. Increasing ionization energy N, O, F

67. Increasing atomic size S , O, Se, C

68. Increasing acidity HOCl, HOBr, HOI

69. Increasing density H2S, O

2, CO

2, NH

3, H

2

70. Increasing thermal stability HF, HCl, HBr, HI

71. Increasing bond enthalpy N2, O

2, F

2, Cl

2

72. Increasing melting point CaF2, CaCl

2, CaBr

2, CaI

2

73. Increasing oxidizing power O, S, Se, Te

74. Increasing oxidizing power F, Cl, Br, I

75. Increasing size B , Be, Li, Na

76. Increasing single bond strength N - N, O - O, F -F

77. Increasing stability of hydrides LiH, NaH, KH, CsH



78. Decreasing pH of aquaeous solution of LiCl, BeCl, MgCl2, AlCl

3

79. Increasing acidic oxide Al2O

3, MgO, SiO

2, P

4O

10

80. Increasing basicity F- , Cl- , Br-, I-

81. Increasing basic strength F-, OH-, NH2

-, CH3

-

82. Increasing boiling point NH3, PH

3, AsH

3, SbH

3

83. Increasing ionization energy B, C, N, O

84. Increasing thermal stability BeCO3, MgCO

3, CaCO

3, BaCO

3

85. Increasing paramagnetism Ca, Al, N, O

86. Increasing ionic character LiBr, NaBr, KBr, RbBr, CsBr

87. Increasing hydration energy Be2+ , Mg2+ , Ca2+, Ba2+, Sr2+

88. Increasing bond angle NH3, PH

3, AsH

3

89. Increasing bond angle NF3, PH

3, AsF

3

90. Increasing bond angle H2O, H

2S, H

2Se

91. Increasing bond angle NF3, NCl

3.

92. Increasing bond angle NO2

+, NO2, NO

2-

93. Increasing bond angle NH3, NF

3

94. Increasing bond angle PH3, PF

3

95. Increasing electronegativity O–, O, O+.



Each entry in column X is in some way related to the entries in columns Y and Z.Match the appropriate entries.

1. X Y Z

(a) Asbestos Molecular sieve air pollutant

(b) Fluorocarbons paramagnetic carcinogen

(c) Lithium oxide reducing agent flurescent paint

(d) Nitric oxide reducing agent electron donor

(e) Zeolites semiconductor ion exchanger

(f) Zinc oxide silicates of Ca + Mg propellent

2. X Y Z

(a) Animal charcol kj K-1 watch spring

(b) Invar cm-1 1.3805 x 10-26

(c) Nichrome Co, Ni sugar refinig

(d) Rydberg Fe, Ni cutlery

(e) Stainless steel Fe, Cr, Ni, C 109677

(f) Boltzmann C, Ca3 ,(PO

4)

2heating element

3. X Y Z

(a) Mica heavy water reinforced plastic

(b) Superphoshate magnesium deuterium oxide

(c) Moderator graphite crystalline insulator

(d) Carborundum layer structure photosynthesis

(e) Carbon fibres high melting fertilizer

(f) Chlorophyll bone ash abrasive

4. X Y Z

(a) Washing soda Fertilizer sodium metal

(b) Luanr caustic Na2SO

4. 10H

2O CaCN

2

(c) Glaubers salt AgNO3

Na2CO

3.10H

2O

(d) Downs cell broken limbs eye lotion

(e) Nitrolim detergents CaSO4.1/2 H

2O

(f) Plater of paris NaCl + CaCl2

heat exhanger

EXERCISE # 2



5. X Y Z

(a) sp hybridization square planar SO2

(b) sp2 hybridization tetrahedral BeH22

(c) sp3 hybridization octrahedral Cu (NH3)

42+

(d) dsp2 hybridization trigonal bipyramidal ClO3

-

(e) d2sp3 hybridization linear PCl5

(f) dsp3 hybridization triangular planar SF6

6. X Y Z

(a) Paint HCl (3 vol.) + HNO3 ( 1vol) laughiing gas

(b) Anaesthetic calcium carbide face lotion

(c) Water gas lithophone acetylene

(d) Aqua regia ZnCO3

CO + H2

(e) Petromax lamps N2O BaSO

4 + ZnS

(f) Calamine fuel dissolves gold

7. X Y Z

(a) Corrosive sublimate PbO white washing

(b) Hypo CaO amphoteric

(c) Litharge HgCl2

fixer

(d) Quicklime Al2O

3.2H

2O isomorphous with white vitriol

(e) Alumina antichlor dry cells

(f) Epsom salt MgSO4.7H

2O plgment

8. X Y Z

(a) Rock salt washing soda pencil lead

(b) Indian saltpetre electrode PH3

(c) Solvay process dilute NaOH mordant

(d) Graphite cubic explosive

(e) Alum NaNO3

Na2CO

3. 10H

2O

(f) Phosphorus KAl (SO4)

2. 12H

2O preservative

9. X Y Z

(a) Calium dolomite alkali metal

(b) Zinc dilute HNO3

Sorel’s cement

(c) Potassium alkaline earth galvanization

(d) Phosphorus violet flame washing soda

(e) Sodium Daniell cell bones

(f) Magnesium Downs process phosphine



10. X Y Z

(a) Aluminium anglesite invar

(b) Tin siderite constituent of 14 carat gold

(c) L e a d corundum Philospher’s wool

(d) Iron ealamine three allotropic forms

(e) Copper cassiterite third most abundant

(f) Zinc azurite storage battery

11. X Y Z

(a) SnS2

Nessler’s reagent yellow pigment

(b) Chrome yellow white pigment brown ring

(c) NH3

Mosaic gold petrol

(d) NO3

- antiknocking changes yellow on heating

(e) ZnO PbCrO4

used decoratively

(f) Pb (C2H

5)

4FeSO

4 + H

2SO

4brown precipitate

12. X Y Z

(a) Two water of crystallization ferrous sulphate styptic reagent

(b) Five water of crystallization Mohr’s salt washing soda

(c) Seven water of crystallization sodium carbonate green vitriol

(d) Six water of crystallization calcium sulphate blue vitriol

(e) Ten water of crystallization copper sulphate stable salt of iron

(f) Twelve water of crystallization alum gypsum

13. X Y Z

(a) Hyphosphorous acid H3PO

4tetrabasic acid

(b) Orthophosphorus acid HPO3

2H attached to P

(c) Hyphosphoric acid H4P

2O

7no H attached to P

(d) Orthophosphoric acid H3PO

3glacial phosphoric acid

(e) Pyrophosphoric acid H3PO

2hydrolysed to H

3PO

3 and H

3SO

4

(f) Metaphosphoric acid H4P

2O

61H attached to P

14. X Y Z

(a) V2O

5KClO

3autocatalyst

(b) Fe hydrogenation polymerization of ethene

(c) MnO2

SO3

vansapati

(d) Mn2+ Ziegler - Natta Haber process

(e) Ni NH3

Contact process

(f) Ti MnO4

- + oxalic acid Oxygen



15. X Y Z

(a) Ammonia auto- oxidation antacid

(b) Oxygen slaked lime volumetric analysis

(c) Hydrogen peroxide NaHCO3

bleaching powder

(d) Chlorine Ostwald process paramagnetic

(e) Baking soda photography 2-ethylanthraquinone

(f) Sodium thiosulphate two unpaired electrons nitric oxide

16. X Y Z

(a) K+, ions excess of KI (aq) red precipitate

(b) Fe3+ ions HCl (aq) Nessler’s reagent

(c) Cu2+ ions sodium cobaltinitrite white precipitate

(d) HgCl2(aq) starch solution chorcolate precipitate

(e) Pb NO3 (aq) SCN- ions blue colour

(f) I2(aq) ferrocyanide ions yellow precipitate



STATE TRUE OR FALSE :

1. The softness of alkali metals decreases from Lithium to Caesium.

2. Lithium is the strongest reducing agent in aqueous solution because Li+ has very large hydrationenergy.

3. Sodium and potassium when mixed in equimolecular amounts form liquid solution.

4. All the alkali metal cations are coloured and paramagnetic.

'5. In the polymerisation of alkadienes, sodium is used as a catalyst.

6. Sodium amalgam is more reactive than metal lie sodium.

7. Zairvogel process is used for the extraction of silver.

8. Causticization process is used for the preparation of caustic potash.

9. Castner process, for manufacture of metallic sodium involves the electrolysis of fused NaOH.

10. Solubility of NaOH in water increases with rise in temperature.

11. When CuCN (white ppt.) dissolves in KCN (aq), the freezing point of KCN solution is raised.

12. Potassium and Caesium are used as electron source in photo electric cells.

13. The surface of a silver frying pan turns black when as Ommelette is cooked in it.

14. Parke's process for de-silverization of argentiferous lead is based on principle of distibution.

15. Cuprous chloride is used in gas analysis for absorption of CO and C2H

2 gases.

16. Schweitzer's reagent is a mixture of cupric acetate and acetic acid.

17. The electronic configuration of alkaline earth metals is [Inerg gas] ns2.

EXERCISE # 3



18. In [BeF3]–, beryllium is sp2 hybridized.

19. The solubility product of Be(OH)2 is miximum.

20. The maximum tendency of complex formation is of Barium.

21. Strontium salts impart crimson red colour in Bunsen burner flame.

22. Beryllium shows diagonal relationship with silicon.

23. Lithopone is a mixture of BaSO4 and ZnS.

24. Barium shows + 1 oxidation state in barium peroxide.

25. Calcium sulphate hemihydrate is plaster of paris.

26. Formula of slaked lime is Ca(OH)2.

27. Zinc chloride solution precipitates normal zinc carbonate on treatment with sodium bicarbonatesolution.

28. Alkaline earth metals do not form solid bicarbonates.

29. Sorel's cement is MgCl2, 5MgO, xH

2O and is used for fixing tiles.

30. Aqueous suspension of Mg(OH)2 is known as milk of magnesia.

31. Anhydrone is magnesium perchlorate.

32. The green coloured pigment chlorophyll present in plants contains cobalt.

33. Beryllium chloride exists as a polymer.

34. Baryta water is aqueous solution of Ba(OH)2.

35. Barium sulphate does not dissolve in water because it has low lattice energy.

36. Beryllium and magnesium salts do not impaart any colour to the flame.



37. Sulphur dioxide turns lime water milky.

38. When carbon dioxide gas is passed through an aqueous suspension of gypsom saturated with ammo-nia, ammonium sulphate and CaCO

3 are obtained.

39. Magnesium oxide is used as an acidic flux in metallurgy to remove acidic impurities.

40. Polarizing power of Be++ is greater than Li+.

41. Anhydrite is anhydrous calcium sulphate.

42. Boracic acid is a tribasic strong acid.

43. Aluminium is the most abundant element is the earth's crust.

44. Borax is chemically sodium tetraborate deca hydrate.

45. The decreasing order of Lewis acid strength of boron halides is :

BBr3 > BCl

3 > BF

3

46. The basic nature of hydroxides of elements increases from top to bottom in the IIIA group.

47. Boron does not form tripositive ion.

48. Benzene is fairly reactive where as inorganic benzene is unreactive compound.

49. Hybridization of boron in borate ion (BO3

3–) is sp2.

50. Boric acid is the most stable oxy acid of boron.

51. Lapis Lazuli is a beautiful blue coloured semiprecious stone belonging to the family of sodium aluminosilicate.

52. Serpecks process is used for the purification of Bauxite containing rutile as the main impurity.

53. Salt water corrodes aluminium at a faster rate.

54. The inert pair effect increases down the IIIA group.

55. Thallium (+ 1) is a powerful reducing agent.



56. BI3 is the strongest Lewis acid because the back bonding by iodine atom is minimum.

57. Silicon shows diagonal relationship with boron.

58. Silicon carbide (SiC) is corundum.

59. Thermite process is used for the manufacture of wrought iron.

60. When AlH3 accepts one pair of electrons from hydride ion (H–), its hybridization changes from sp2 to

sp3.

61. Fusion of borax with ammonium chloride produces boron nitride.

62. Hardest substance next to diamond is the borundum.

63. Boron halides in organic solvents exist as dimers.

64. In Hall and Haroult's process, aluminium is extracted by electrolysis of AlCl3 dissolved in fused

cryolite.

65. Chrome alum contains potassium as well as chromium.

66. Ferric alum is white coloured crystalline solid.

67. A small crystal of silver alum grows in size when suspended in a solution of ferric alum because thetwo are isomorphous.

68. The residue left on strong heating of potash alum contains K2O and Al

2O

3.

69. Diborane on heating with ammonia yields borazine.

70. TlI3 is non existent compound.

71. The dimer of AlCl3 contains covalent and dative bonds.

72. Pure silicon is obtained by thermal decomposition of monosilane.

73. All the tetrachloride of IVA group elements are fuming liquids except carbon tetrachloride.

74. Silica is a gaint covalent molecule having high melting point.



75. The basic unit of SiO2 is SiO

44–.

76. Si – O bond strength is greater that Si – Si bond.

77. Crystalline silicon has diamond like structure.

78. Stannous chloride is non linear molecule.

79. Carbon dissolves in caustic potash solution to form potassium carbonate and hydrogen gas.

80. Producer gas contains carbon monoxite and hydrogen gas.

81. Lead does not react with NaOH solution.

82. Sugar of lead is basic lead acetate.

83. Impure tin can be refined by liquation.

84. Combination of hot tin with dry chlorine produces anhydrous stannous chloride.

85. Tin oxide is an acidic oxide.

86. There are three allotropic forms of tin.

87. Lead does not show allotropy.

88. Lead (II) chloride is soluble is hot water but not is cold water.

89. R3SiCl on hydrolysis produces

R3Si – O – SiR

3

90. Maximum catenation property is exhibited by carbon.

91. Pb is used to make protective coatings against radiation protection.

92. Carbon monoxide combines with iron to form iron pentacarbonyl.

93. Plumbosolvency is the phenomenon of disolution of lead in water which contains ions such as NO3

–

, CH3COO–, etc.



94. Solder is a low melting alloy of lead and tin.

95. Lead is the last decay product of natural radio active series.

96. PbI4 does not exist.

97. Elements of group 15 are called pnicogens.

98. Nitrogen is chemically inert under ordinary conditions because of the absence of bond polarity.

99. Shape of ammonia molecule is pyramidal.

100. N3H is the acidic hydride of nitrogen.

101. Red phosphorus reacts with hot Ba(OH)2 solution and gives phosphine.

102. The P – P – P bond angle is 109º28' as the P4 molecule is tetrahedral in shape.

103. P4 molecule is strained and hence is chemically reactive.

104. Dipole moment of ammonia is lower than NF3.

105. NCl5 exists white PCl

5 is unknown.

106. PCl3 on hydrolysis produces a dibasic and a monobasic acid.

107. Out of nitrogen trihalides, NF3 is the weakest Lewis base.

108. Lightning in the clouds converts atmospheric nitrogen partially into hydroxyl amine.

109. Nitrous acid behaves only as reducing agent.

110. The N – O bond distance in NO3

– radical is greater than that in NO2

– ion.

111. N2O

4 molecule is diamagnetic and colourless.

112. N2O

5 is nitronium nitrate.

113. A mixture of conc. HNO3 and conc. HCl is called nitrating mixture.



114. Aqua regia dissolves gold by forming chloroauric H [AuCl4].

115. The decreasing order of boiling point of 15th group hydrides is :

NH3 > PH

3 > AsH

3 > SbH

3

116. In liquid ammonia, ammonium chloride behaves as ammono acid.

117. Sodium in liquid ammonia is a reducing agent in Birch reduction.

118. An alkyne, R1 – C ≡ C – R

2 yields transalkene on reduction with sodium in liquid ammonia.

119. Nitrogen tri-chloride is a highly explosive liquid.

120. Arsenic does not form a pentachloride.

121. Antimony trichloride is called as butter of antimony.

122. Potassium antimonyl tartrate is a constituent of Fehling's solution.

123. On addition of a large excess of water to BiCl3, a white turbidity is produced which is of BiOCl.

124. All the ammonium compounds contain electrovalent, covalent and co-ordinate bond.

125. A proton participates in co-ordinate bond formation.

126. Hypophosphorous acid is a tribasic acid.

127. Concentrated sulphuric acid is a powerful dehydrating agent.

128. Sulphur can extend its covalency due to the availability of 3d-sub-shell.

129. Ozone an allotrope of oxygen, is diamagnetic in nature.

130. Hybridization of Te in TeCl4 is sp3.

131. Sulphur does not form basic oxide.

132. The oxidation state of sulphur varies from - 2 to + 6.



133. SO2 behaves like reducing agent only.

134. H2S turns lead acetate paper silvery black due to the formation of PbS.

135. BaSO4 is useful for patients as barium meal for X-rays.

136. Both SO3 and SeO

3 are cyclic compounds in solid state.

137. Bond order in ozone is 1.5.

138. Bond angle in VIth group hydrides decreases from H2O to H

2Te due to decreasing electronegativity

and increasing atomic size of central atom.

139. Iodine is purified by sublimation.

140. Electrolysis of ICl in pyridine gives iodine at cathode.

141. In aqueous solution, chlorine is a stronger oxidising agent than fluorine.

142. All chlorides are electrovalent compound.

143. MgCl2.6H

2O on heating gives anhydrous MgCl

2.

144. HCl is covalent molecule in gaseous state.

145. It is easy to prepare fluorine by chemical methods.

146. Reactivity of halogens decreases from bottom to top in the group.

147. Chlorine is collected by upward displacement of air.

148. Bleaching action of bleaching powder is due to OCl– ion.

149. Hydrochloric acid is a stronger acid than hydroiodic acid.

150. The dipole moment of hydrogen halides decreases in the order

HF > HCl > HBr > HI

151. Solution of hydrogen chloride gas in benzene evolves hydrogen gas on reaction with metallic zinc.



152. Liquid HCl contains intermolecular H-bonding.

153. Oxidation state of fluorine in OF2 is + 2.

154. AgCl is more soluble in very concentrated solution of NaCl than in pure water.

155. Dipole moment of IF5 is zero.

156. Interhalogen compounds are characterized by the presence of even number of atoms and even numberof electrons.

157. Chlorine does not support combustion but a paper dipped in turpentine oil catches fire in contact withchlorine gas.

158. Chlorine gas undergoes disproportionation when treated with alkali solution.

159. Hypohalites when heated undergo disproportionation to give halide and halate ion.

160. Iodide is a better nucleophile than bromide.

161. Least polarizability is of fluoride ion.

162. Bromide ions turn starch iodide paper blue.

163. Interhalogen compounds of type AB3 possess T-shaped structure.

164. Hybridization of central halogen in interhalogens of type AB5 is sp3d2.

165. Perbromic acid is unknown.

166. Among hypohalous acids, HOCl has minimum pKa value.

167. Hydride ion is unstable in aqueous solutions.

168. In glacial acetic acid, H+ exists as CH3 COOH

2+.

169. Hybridization of chlorine in ClO2

– ion is sp3.

170. HOCl first gives a red colour with blue litmus and then bleaches it.



171. Both potassium ferrocyanide and potassium ferricyanide are diamagnetic.

172. Prussion blue is ferric ferrocyanide.

173. Mohr's salt is a double sulphate.

174. Ferrous salt can be distinguished from ferric salt by adding acidified KMnO4.

175. Compounds of transitional metals in higher oxidation state are covalent while in lower O.S. of themetal, they are ionic.

176. The lowest oxidation state of a transition metal is + 2.

177. The complex [NICl4]–– has tetrahedral geometry and is paramagnetic in nature.

178. Ferromagnetic substances possess very high paramagnetism.

179. In a complex molecule or ion, the central metal ion with vacant d-orbitals behaves as a Lewis acid.

180. The 6d-transition series starts with thorium and ends at Ekamercury.

181. Transition elements have larger atomic radii than s- and p-Block elements.

182. Cadmium is the last element of 4d-transition series.

183. The atomic radii of Zr and Hf are the same due to lanthanide contraction.

184. Platinum is used in resistance thermometers.

185. Equivalent weight of potassium dichromate in acidic medium is one third of its molecular weight.

186. Brass is an alloy of copper and zinc.

187. German silver contains fifty percent silver.

188. Ions having (n - 1) d0 or (n - 1) d10 configuration are intense blue coloured.

189. Fischer salt is potassium cobaltinitrite.



190. Ti3+ is coloured white Ti4+ is colourless.

191. A mixture of R3Al and TiCl

4 is Ziegler-Natta catalyst.

192. All ligands are Lewis bases.

193. The stability of Fe3+ ion is due to half filled 3d-orbitals.

194. The ionization potential values of transition elements are less than p-Block elements.

195. FeO is acidic while Fe2O

3 is basic oxide of iron.

196. The transition metal with highest melting and boiling point is mercury.

197. Stable oxidation state of copper is + 1.

198. The order of reactivity of halogens with transitional elements is F > Cl > Br > I.

199. Strongest metallic bond is in tungston.

200. Fe2+ ion is unstable in aerated water with respect to oxidation.

201. Third and fourth periods are long periods of periodic table.

202. The second ionization potential of oxygen is higher than that of nitrogen.

203. In inner transitional elements, the outer two shells are partially filled with electrons.

204. The common oxidation state of lanthanides is + 3.

205. The degree of hydration of a cation increase with decrease in ionic size.

206. Caesium has minimum work function in alkali metals.

20.7 All the lanthanides are radioactive.

208. Transitional elements exhibit horizontal as well as vertical similarity in their properties in theirgroups.

209. The formation of dinegative or trinegative ion is an endothermic process.



210. Elements showing diagonal similarity have nearly the same value of electronegativity.

211. The softness of 1A metals increases down the group with increasing atomic number.

212. Atomic size of element increases from right to left in a period.

213. First ionization energies of O, N and C are in the order C < O < N.

214. The conductance of aqueous alkali metal cations increases from top to bottom in the group.

215. The ions Na+, Mg++ and Al+++ are iso-electronic and hence the same ionic radii.

216. Zirconium and Hafnium are twins elements of the periodic table.

217. The second ionization energy of an element is always greater than its first ionization energy.

218. Hydrogen shows + 1 and - 1 oxidation states.

219. Hydrogen bonding also exists in heavy water.

220. O – D ... O bond is slightly stronger than O – H ... O bond.

221. Hydrides of boron are called borances.

222. Hydrogen peroxide is a weak dibasic acid.

223. When PbO2 reacts with a dilute acid, it gives hydrogen perioxide.

224. Water behaves as a Lowry Bronsted acid as well as a base.

225. The heaviest isotope of hydrogne is three times heavier than hydrogen.

226. One neutron and two proton are present in the deuterium nucleus.

227. Liquid hydrogen is used as a fuel in aeroplanes.

228. Moist hydrogen is not dried by passing through concentrated H2SO

4 as it may catch fire.

229. Bleaching action of H2O

2 is temporary and is due to reduction.



230. Hydrogenation of an alkyne, R – C ≡ C – R' in the presence of Pt gives cis-alkene.

231. The simplest borane is BH3.

232. Heavy water is produced by exhaustive electrolysis of water under alkaline conditions.

233. Water is more viscous than heavy water.

234. Hydrogen peroxide is a thermodynamically unstable liquid.

235. Normal hydrogen peroxide solution is '5.6 vol' H2O

2

236. When hydrogen gas is passed through a porous plug under ordinary conditions, it is heated up, becauseits inversion temperature is low.

237. Acidic KMnO4 is decolourized by passing hydrogen gas through the solution.

238. Almost pure para hydrogen exists at 20 K.

239. It is impossible to prepare 100% pure ortho hydrogen.

240. Bond order of H2

+ as well as H2

– is 6½ and both are paramagnetic.



FILL IN THE BLANKS :

1. A standard solution of sodium hydroxide cannot be prepared by direct weighingbecause . . . . . . . . . . . . . . . . . . . . . . . . . .

2. Phenomenon of crumbling to powder of sodium carbonate crystals on exposure to airis known as . . . . . . . . . . . . . . . . . . . . . . . . . .

3. Silver chloride is sparingly soluble in water because its lattice energy is greater than. . . . . . . . . . . . . . . . . . . . . . . . . . energy.

4. Silver chloride dissolves in excess of potassium cyanide solution to give complexcompound . . . . . . . . . . . . . . . . . . . . . . . . . .

5. Fusion mixture contains . . . . . . . . . . . . . . . . . . . . . . . . . .

6. Solvay process is used for the manufacture of ..........................

7. German silver contains .......................... percent silver.

8. Cuprous ion is . . . . . . . . . . . . . . . . . . . . . . . . . . and . . . . . . . . . . . . . . . . . . . . . . . . . .

9. Metallic sodium is prepared in Down's process by the electrolysis of molten. . . . . . . . . . . . . . . . . . . . . . . . . .

10. Potassium bicarbonate cannot be prepared by solvay process because ..........................

11. Solution of alkali metals in liquid ammonia conducts electricity due to. . . . . . . . . . . . . . . . . . . . . . . . . .

12. Radioactive alkali metal is . . . . . . . . . . . . . . . . . . . . . . . . . .

13. Addition of potassium iodide to copper sulphate results in the liberation of.. . . . . . . . . . . . . . . . . . . . . . . . . and formation of a white precipitate of . . . . . . . . . . . . . . . . . . . . . . . . . .

14. Ductility and malleability of silver is .......................... than gold.

EXERCISE # 4



15. Blister copper is .. . . . . . . . . . . . . . . . . . . . . . . . . copper.

16. Sodium loses its lusture on exposure to air due to the formation of ..........................

17. Matte consists mainly of .......................... with a little

18. Alkali metal elements show a sudden .......................... in second ionization potential.

19. Hardest alkali metal is . . . . . . . . . . . . . . . . . . . . . . . . . .

20. All the alkali metals crystallize is .......................... arrangement.

21. Among silver halides, maximum lattice energy is of ..........................

22. .......................... is the best conductor of electricity.

23. Copper is used in radiators because of its good .......................... condutitivity.

24. The solubility of cupric hydroxide in ammonia is due to the formation of a complexcompound having the formula . . . . . . . . . . . . . . . . . . . . . . . . . .

25. .......................... tunch silver is hundred percent pure.

26. Twenty four carat gold is .......................... percent pure.

27. Cyanide process is used for the extraction of ... . . . . . . . . . . . . . . . . . . . . . . . as well as. . . . . . . . . . . . . . . . . . . . . . . . . .

28. Alloy of copper with tin is called ..........................

29. During besemerization, .......................... and .......................... react to form blistercopper.

30. In copper sulphate penta hydrate .......................... water molecules are co-ordinatesto the Cu++ ion.

31. Types of bonds present in CuSO4. 5H

2O are . . . . . . . . . . . . . . . . . . . . . . . . . . and

. . . . . . . . . . . . . . . . . . . . . . . . . . .

32. Water glass is . . . . . . . . . . . . . . . . . . . . . . . . . .



33. Cuprous cyanide dissolves in potassium cyanide to form ..........................

34. Vedigris is . . . . . . . . . . . . . . . . . . . . . . . . . .

35. Lunar caustic is stored in dark brown battles to ..... . . . . . . . . . . . . . . . . . . . . . because it is. . . . . . . . . . . . . . . . . . . . . . . . . .

36. The only chloride which turns black on treatment with ammonium hydroxide is. . . . . . . . . . . . . . . . . . . . . . . . . .

37. Mercury (II) chloride does not give .......................... test for chloride ion.

38. The fastest setting component of cement is ..........................

39. Hybridization of mercury in mercuric chloride is ..........................

40. When MgCl2, 6H

2O is heated, . . . . . . . . . . . . . . . . . . . . . . . . . . is obtained.

41. Among HgCl2 and Hg

2Cl

2 .......................... is deadly poisonous while is used as a

purgative.

42. Radium was isolated from .. . . . . . . . . . . . . . . . . . . . . . . . . by . . . . . . . . . . . . . . . . . . . . . . . . . .

43. Freezing point of heavy water is ..........................

44. .......................... is used as a fluorescent paint.

45. Zinc oxide becomes .......................... on heating and again becomes .......................... on cooling.

46. Anhydrous MgCl2is obtained by heating the hydrated salt with ..........................

47. Plaster of paris is made by heating .......................... to about 120ºC and its formula is ..........................

48. Weakest metallic bond is present in ..........................

49. Galvanization of iron denotes coating with ..........................

50. Dipositive zinc exhibits .......................... (paramagnetism/diamagnetism).



51. Burnt lime is . . . . . . . . . . . . . . . . . . . . . . . . . .

52. Ore of cadmium is . . . . . . . . . . . . . . . . . . . . . . . . . .

53. Luca's reagent is . . . . . . . . . . . . . . . . . . . . . . . . . .

54. The best method for separation of a metal from its amalgam is ..........................

55. Mercury does not form amalgam with .......................... group elements of modernperiodic table.

56. The function of sand in mortar is to .......................... of the mass.

57. Raw materials used for the manufacture of cement are .. . . . . . . . . . . . . . . . . . . . . . . . . and. . . . . . . . . . . . . . . . . . . . . . . . . .

58. Setting of cement is process and is accompained by .......................... of heat.

59. Frankland reagents are . . . . . . . . . . . . . . . . . . . . . . . . . .

60. Manimata disease is caused by intake of ...... . . . . . . . . . . . . . . . . . . . .

61. Speller is . . . . . . . . . . . . . . . . . . . . . . . . . . zinc.

62. In the thermite process .......................... is used as reducting agent

63. An alloy of copper with aluminium having beautiful golden colour is known as. . . . . . . . . . . . . . . . . . . . . . . . . .

64. Hydrides of boron are called .... . . . . . . . . . . . . . . . . . . . . . .

65. All the boron halides are ..........................

66. Alums are represented by the general formula ...... . . . . . . . . . . . . . . . . . . . .

67. A mixture of aluminium powder and ammonium nitrate is known as. . . . . . . . . . . . . . . . . . . . . . . . . .

68. On treatment with conc. HNO3 aluminium . . . . . . . . . . . . . . . . . . . . . . . . . .



69. Among boron halides .......................... is the weakest Lewis acid.

70. Aluminium dissolves in alkali with evolution of .......................... and formation ofsoluble . . . . . . . . . . . . . . . . . . . . . . . . . .

71. Anhydrous aluminium chloride is a Lewsi acid because it can ... . . . . . . . . . . . . . . . . . . . . . . .electrons.

72. [AlH4]– possesses .. . . . . . . . . . . . . . . . . . . . . . . . . shape.

73. Duralumin coated with aluminium layer is called ... . . . . . . . . . . . . . . . . . . . . . . .

74. .......................... gives a green coloured bead in the borax bead test.

75. Formula of colemanite is . . . . . . . . . . . . . . . . . . . . . . . . . .

76. When NaBH4 is heated with iodine in diglyme ....... . . . . . . . . . . . . . . . . . . . is obtained.

77. The lowest melting element of IIIA group is ..........................

78. An aqueous solution of alum is .......................... due to .......................... hydrolysis.

79. Molecular formula of inorganic benzene is ..........................

80. In the presence of polyhydroxy compounds like mannitol, boric acid acid as. . . . . . . . . . . . . . . . . . . . . . . . . . acid.

81. Diamond can be converted to graphite by heating to ..........................

82. The hardest substance known is .. . . . . . . . . . . . . . . . . . . . . . . . .

83. The C – C bond length in graphite is .......................... than that in diamond.

84. Hybridization of carbon in graphite is . . . . . . . . . . . . . . . . . . . . . . . . . . while in diamond it is. . . . . . . . . . . . . . . . . . . . . . . . . . hybridized.

85. Purest form of amorphous carbon is ..... . . . . . . . . . . . . . . . . . . . . .

86. Bond order in carbon monoxide is ..........................



87. Hybridization of carbon in CO molecule is ..........................

88. Valency of carbon in CO molecule is ..........................

89. CO2 is absorbed in the solution of .... . . . . . . . . . . . . . . . . . . . . . . white CO is absorbed by

. . . . . . . . . . . . . . . . . . . . . . . . . .

90. CO2 is absorbed by plants in the presence of sun light an chlorophyll to form

carbohydrates, the process is known as ...... . . . . . . . . . . . . . . . . . . . .

91. The electrical conductor allotropic forms of carbon are .... . . . . . . . . . . . . . . . . . . . . . . and. . . . . . . . . . . . . . . . . . . . . . . . . .

92. The oxide of lead used in storage battery is ..........................

93. Sindur is . . . . . . . . . . . . . . . . . . . . . . . . . . while vermilion is . . . . . . . . . . . . . . . . . . . . . . . . . .

94. The most stable allotrope of carbon at high temperatures is ..........................

95. Carbon monoxide is used in the purification of .......................... by ..........................process.

96. Nickel combines with carbon monoxide to form ... . . . . . . . . . . . . . . . . . . . . . . . which has. . . . . . . . . . . . . . . . . . . . . . . . . . shape.

97. Cassiterite is an ore of ..........................

98. Bronze is an alloy of .... . . . . . . . . . . . . . . . . . . . . . .

99. Dry ice is . . . . . . . . . . . . . . . . . . . . . . . . . .

100. Dry ice is a .......................... solid.

101. Carbon dioxide is a .......................... of combustion while CO burns itself with a. . . . . . . . . . . . . . . . . . . . . . . . . . f lame.

102. Carbon dioxide oxidises carbon to ..........................

103. The process by which dry ice is directly converted to its gaseous form is known as. . . . . . . . . . . . . . . . . . . . . . . . . .



104. Dipole moment of carbon disulphide is ... . . . . . . . . . . . . . . . . . . . . . . .

105. CO2 molecule has . . . . . . . . . . . . . . . . . . . . . . . . . . shape.

106. Plumbo plumbic oxide is also called ... . . . . . . . . . . . . . . . . . . . . . . .

107. Lead containing glass is .... . . . . . . . . . . . . . . . . . . . . . . glass.

108. Glass is soluble in .......................... due to the formation of ..........................

109. Components of pyrex glass are . . . . . . . . . . . . . . . . . . . . . . . . . . of . . . . . . . . . . . . . . . . . . . . . . . . . . and. . . . . . . . . . . . . . . . . . . . . . . . . .

110. White lead is . . . . . . . . . . . . . . . . . . . . . . . . . . salt.

111. Germanium is used as a . . . . . . . . . . . . . . . . . . . . . . . . . .

112. Second most abundant element in the earth's crust is ..........................

113. Graphite is also known as ... . . . . . . . . . . . . . . . . . . . . . . .

114. Butter of tin is . . . . . . . . . . . . . . . . . . . . . . . . . .

115. Components of ordinary glass are . . . . . . . . . . . . . . . . . . . . . . . . . . and .. . . . . . . . . . . . . . . . . . . . . . . . .

116. Out of PbCl2 and PbCl

4 .......................... is more ionic in nature.

117. Crystalline form of silica is called ..........................

118. Maximum number of compounds are formed by .. . . . . . . . . . . . . . . . . . . . . . . . .

119. Nitric oxide is a ... . . . . . . . . . . . . . . . . . . . . . . . and .... . . . . . . . . . . . . . . . . . . . . . . oxide of nitrogen

120. Nitrous oxide forms a ...... . . . . . . . . . . . . . . . . . . . . molecule.

121. Phosphorus pentoxide reacts with nitric acid to yield ..........................

122. Bleaching powder oxidises ammonia to .. . . . . . . . . . . . . . . . . . . . . . . . .



123. Orthophosphorous acid on heating undergoes ... . . . . . . . . . . . . . . . . . . . . . . . to give. . . . . . . . . . . . . . . . . . . . . . . . . . and . . . . . . . . . . . . . . . . . . . . . . . . . .

124. Phosphine is obtained when white phosphorus is boiled with ... . . . . . . . . . . . . . . . . . . . . . . .solution.

125. When white phosphorous is heated with iodine, it is converted into ..........................

126. Red phosphorus is less reactive than white phosphorus because it has ..........................

127. The conversion of atmospheric nitrogen into useful compounds is known as. . . . . . . . . . . . . . . . . . . . . . . . . .

128. NO2 is . . . . . . . . . . . . . . . . . . . . . . . . . . coloured and .. . . . . . . . . . . . . . . . . . . . . . . . . in nature.

129. Nitric oxide molecule contains .......................... unpaired electron / electrons.

130. Nitrous acid behaves as . . . . . . . . . . . . . . . . . . . . . . . . . . and . . . . . . . . . . . . . . . . . . . . . . . . . . agent.

131. Phosphorus was discovered by .. . . . . . . . . . . . . . . . . . . . . . . . .

132. Hydrolysis of PCl5 yields . . . . . . . . . . . . . . . . . . . . . . . . . . basic acid and .. . . . . . . . . . . . . . . . . . . . . . . . . basic

acid.

133. Antidote of arsenic poisoning is ..........................

134. Pyrophosphoric acid forms .......................... types of salts.

135. Oxidation state of phosphorus in magnesium pyrophosphate is ..........................

136. Dipole moment of NF3 is . . . . . . . . . . . . . . . . . . . . . . . . . . than NH

3.

137. SbCl3 on hydrolysis produces a white turbidity of ..........................

138. When HCl is added to a solution of As2S

3 in yellow ammonium sulphide, a precipitate

of . . . . . . . . . . . . . . . . . . . . . . . . . . is obtained.

139. Calcium cyanamide on hydrolysis with superheated steam under pressure gives. . . . . . . . . . . . . . . . . . . . . . . . . . as the main product.



140. The H – P – H bond angle in PH3 is .......................... than H – N – H bond angle

in NH3.

141. An aqueous solution of phosphine is .......................... towards litmus.

142. Dense white fumes of .......................... are produced when phosphine catches firein air.

143. N2O

5 dissolves in water with a ..........................sound and yields ..........................

144. NO2 is . . . . . . . . . . . . . . . . . . . . . . . . . . acid anhydride.

145. Basic calcium nitrate is known as ... . . . . . . . . . . . . . . . . . . . . . . .

146. An aqueous solution of ferrous sulphate absorbs .......................... and turns.. . . . . . . . . . . . . . . . . . . . . . . . . due to the formation of . . . . . . . . . . . . . . . . . . . . . . . . . .

147. ... . . . . . . . . . . . . . . . . . . . . . . . radical is detected by ring rest.

148. All the N – O bond lengths in NO3

– are equal is explained by ..........................

149. An aqueous solution of ammonia contains .......................... and ..........................

150. Excess of ammonia reacts with cupric sulphate to give a blue coloured complexhaving the formula . . . . . . . . . . . . . . . . . . . . . . . . . .

151. The oxide of nitrogen soluble in methyl alcohol is ..........................

152. ... . . . . . . . . . . . . . . . . . . . . . . . produces reddish brown fumes of .. . . . . . . . . . . . . . . . . . . . . . . . . in air.

153. 68% aqueous HNO3 is an .. . . . . . . . . . . . . . . . . . . . . . . . . mixture.

154. .......................... phosphorus is reactive because of its highly strained tetrahedralstructure.

155. Metaphosphoric acid coagulates . . . . . . . . . . . . . . . . . . . . . . . . . .

156. Long contact with phosphorus vapours causes a disease known as ..........................

157. A fertilizer containing N, H and O is ..........................



158. Conc. HNO3 turns brown in contact with sunlight due to ..........................

159. Oxygen is absorbed by an alkaline solution of .. . . . . . . . . . . . . . . . . . . . . . . . . which turns. . . . . . . . . . . . . . . . . . . . . . . . . .

160. Sulphur acts as a .......................... agent in the vulcanization of rubber.

161. The most abundant chalcogen in the earth's crust is ..........................

162. Rhombic and monoclinic sulphur are two .......................... of sulphur.

163. .......................... is used for pickling of metal surfaces.

164. The catalyst used in the oxidation of SO2 to SO

3 is . . . . . . . . . . . . . . . . . . . . . . . . . .

165. Ozone is an .......................... form of oxygen.

166. Conc. H2SO

4 dissolves SO

3 to give . . . . . . . . . . . . . . . . . . . . . . . . . .

167. An aqueous solution of SO2 is called .. . . . . . . . . . . . . . . . . . . . . . . . . acid.

168. Oxygen molecule contains ... . . . . . . . . . . . . . . . . . . . . . . . unpaired electrons and shows. . . . . . . . . . . . . . . . . . . . . . . . . .

169. Sulphur reduces hot and conc. H2SO

4 to . . . . . . . . . . . . . . . . . . . . . . . . . . and conc. HNO

3 t o

. . . . . . . . . . . . . . . . . . . . . . . . . .

170. Metallic oxides react with water to form .......................... and non metallic osidesform . . . . . . . . . . . . . . . . . . . . . . . . . .

171. Sulphure acid is a mineral .......................... but phosphoric acid is not.

172. Bleaching action of SO2 is due to .......................... and hence is ..........................

173. When ClO2 is passed through an alkaline solution of sodium peroxide

. . . . . . . . . . . . . . . . . . . . . . . . . . and . . . . . . . . . . . . . . . . . . . . . . . . . . are obtained.

174. The molecules of H2O

2 and F

2O

2 have the .. . . . . . . . . . . . . . . . . . . . . . . . . shape.

175. The best absorbent for ozone is ..........................



176. Maximum covalency of sulphur is . . . . . . . . . . . . . . . . . . . . . . . . . .

177. Atomicity of selenium is . . . . . . . . . . . . . . . . . . . . . . . . . .

178. Sodium thiosulphate is also called ... . . . . . . . . . . . . . . . . . . . . . . .

179. The acidic nature of hydrogen sulphide is due to ..........................

180. On strong heating SO2 decomposes into and .... . . . . . . . . . . . . . . . . . . . . . .

181. Sodium thiosulphate on reacting with chlorine is . . . . . . . . . . . . . . . . . . . . . . . . . . to. . . . . . . . . . . . . . . . . . . . . . . . . .

182. Di-thionic acid contains .......................... linkage.

183. Iodine oxidises hypo to ... . . . . . . . . . . . . . . . . . . . . . . .

184. The viscous natrure of conc. H2SO

4 is due to the presence of ..........................

185. In the conversion of ethanol to ether, conc. H2SO

4 acts like .......................... agent

as well as a . . . . . . . . . . . . . . . . . . . . . . . . . .

186. The reaction between H2S and NaHSO

3 gives .......................... as the main product.

187. When SO2 is bubbled through aqueous solution of CuSO

4 in the presence of potassium

thiocyanate, the produt is . . . . . . . . . . . . . . . . . . . . . . . . . .

188. A mixture of sulphur dioxide gas, air and water vapour when passed over heatedsodium chloride gives . . . . . . . . . . . . . . . . . . . . . . . . . .

189. Halogen having maximum metallic nature is . . . . . . . . . . . . . . . . . . . . . . . . . .

190. The only non-metallic liquid at room temperature is ..........................

191. Among the hydrogen halides, . . . . . . . . . . . . . . . . . . . . . . . . . . has maximum dipole moment.

192. .......................... acid gives hypo .......................... ion (hydrobromic, hypobromous,perbromic ; bromite, bromic, perbromate).



193. Among the halide ions, .......................... is the strongest reducing agent.

194. Radioactive halogen is . . . . . . . . . . . . . . . . . . . . . . . . . .

195. Of all the halogens, only .......................... forms polyhalide ion.

196. The halogen which is most reactive in the halogenation of alkanes under sunlight is. . . . . . . . . . . . . . . . . . . . . . . . . . (Cl

2, Br

2, I

2).

197. Bromine gives .......................... on reaction with moist sulphur dioxide.

198. Halogens react with one another to form .......................... compounds.

199. Hypo dissolves AgBr by forming .... . . . . . . . . . . . . . . . . . . . . . . ion.

200. The increase in the solubility of iodine in an aqueous solution of potassium iodide isdue to the formation of .. . . . . . . . . . . . . . . . . . . . . . . . .

201. Iodine reacts with hot NaOH solution the products are NaI and ..........................

202. The halide ion which is most difficult to oxidise is ..........................

203. Silver fluoride is fairly .......................... in water.

204. In contact with air, bleaching powder loses its bleaching action due to. . . . . . . . . . . . . . . . . . . . . . . . . .

205. Iodine displaces chlorine from potassium chlorate due to its .......................... naturethan chlorine.

206. Highest oxidation state exhibited by bromine is ......... . . . . . . . . . . . . . . . . .

207. .. . . . . . . . . . . . . . . . . . . . . . . . . has maximum electron affinity.

208. ClO2 is paramagnetic in nature because it is .......................... molecule.

209. Tincture of iodine contains . . . . . . . . . . . . . . . . . . . . . . . . . . and .. . . . . . . . . . . . . . . . . . . . . . . . .

210. Chlorine combines with .......................... sulphur dioxide in the presence of comphorto give sulphuryl chloride.



211. Anhydride of hypochlorous acid is ..........................

212. Salts of chlorous acid are called ..........................

213. Strongest acid among hydrogen halides is ... . . . . . . . . . . . . . . . . . . . . . . .

214. Among HClO3, HIO

3 and HBrO

3, HIO

3 is the . . . . . . . . . . . . . . . . . . . . . . . . . . acid.

215. The extreme reactivity of fluorine is due to its .......................... bond disociationenergy.

216. In I3

–, oxidation state of iodine is ..........................

217. ... . . . . . . . . . . . . . . . . . . . . . . . is the substance which removes chlorine from the cloth in theprocess of bleaching.

218. Among the oxyacids of chlorine, .......................... is thermally maximum stable.

219. Dilute HCl oxidises metallic iron to ..........................

220. The actual reducing agent of haematite in the blast furnace is ..........................

221. Galvanized iron has a coating of ..........................

222. The salts . . . . . . . . . . . . . . . . . . . . . . . . . . and .. . . . . . . . . . . . . . . . . . . . . . . . . are isostructural (CuSO4.5H

2O

; MnSO4.4H

2O ; ZnSO

4. 7H

2O, FeSO

4, . 7H

2O),

223. In the basic Bessemer process for the manufacture of steel, the lining of the converteris made of .. . . . . . . . . . . . . . . . . . . . . . . . . The slag formed consits of .. . . . . . . . . . . . . . . . . . . . . . . . .

224. Ferric ion is .......................... stable than ferrous ion.

225. Iodide ion .......................... ferric ion and is itself converted into ..........................

226. Chemically rust is . . . . . . . . . . . . . . . . . . . . . . . . . .

227. .......................... iron is hardest form of iron.

228. Steel is malleable and ductile when the carbon content is .. . . . . . . . . . . . . . . . . . . . . . . . . (low/high).



229. Formula of load stone is .. . . . . . . . . . . . . . . . . . . . . . . . .

230. Ions having (n - 1) d10 configuration are ... . . . . . . . . . . . . . . . . . . . . . . . and ... . . . . . . . . . . . . . . . . . . . . . . .

231. An aqueous solution of ferric chloride is .......................... in colour but turns.. . . . . . . . . . . . . . . . . . . . . . . . . on standing due to the formation of . . . . . . . . . . . . . . . . . . . . . . . . . . by. . . . . . . . . . . . . . . . . . . . . . . . . .

232. Equivalent weight of Mohr's salt is ... . . . . . . . . . . . . . . . . . . . . . . .

233. Wrought iron has .. . . . . . . . . . . . . . . . . . . . . . . . . structure.

234. Cast iron .......................... on sodification (contracts/expands).

235. Rusting of iron is . . . . . . . . . . . . . . . . . . . . . . . . . . process. It requires . . . . . . . . . . . . . . . . . . . . . . . . . . and. . . . . . . . . . . . . . . . . . . . . . . . . .

236. Transitional metal cations form co-ordination complexes due to high ..........................ratio.

237. Variation in the oxidation state of transitional elements is due to the participationof ........ . . . . . . . . . . . . . . . . . . electrons in bond formation in addition to ........ . . . . . . . . . . . . . . . . . .electrons.

238. Pyrolusite on heating with KOH in air produces ..........................

239. Cupric ion in aqueous solution exists as ..........................

240. Each transition series contains .......................... elements.

241. Chromite ore is . . . . . . . . . . . . . . . . . . . . . . . . . .

242. KMnO4 in alkaline medium behaves like (a/an) ... . . . . . . . . . . . . . . . . . . . . . . . agent.

243. Most similar elements are .. . . . . . . . . . . . . . . . . . . . . . . . .

244. The heaviest d-Block element is .. . . . . . . . . . . . . . . . . . . . . . . . .

245. Chromic acid is formed by mixing conc. H2SO

4 in . . . . . . . . . . . . . . . . . . . . . . . . . .



246. Thermal decomposition of K2Cr

2O

7 is a . . . . . . . . . . . . . . . . . . . . . . . . . . reaction.

247. Iron, cobalt and nickel which generally show large paramagnetic nature, are knownas . . . . . . . . . . . . . . . . . . . . . . . . . .

248. In transitional elements, the differentiating electron entres .......................... subshellin preference to ..... . . . . . . . . . . . . . . . . . . . . . subshell.

249. .. . . . . . . . . . . . . . . . . . . . . . . . . can be easily welded.

250. Molten iron obtained from blast furnace is ..........................

251. The blue coloured compound formed by the reaction of Fe 2+ ion with K3 [Fe(CN)

6] is

called . . . . . . . . . . . . . . . . . . . . . . . . . . and its formula is . . . . . . . . . . . . . . . . . . . . . . . . . .

252. In prussian blue, iron exists in .......................... oxidation state.

253. Chromium forms maximum covalent compounds in .. . . . . . . . . . . . . . . . . . . . . . . . . oxidationstate.

254. Vander Waal's radius is regarded as the .......................... of noble gas elements.

255. The diagonally related pairs in the periodic table are .. . . . . . . . . . . . . . . . . . . . . . . . . and. . . . . . . . . . . . . . . . . . . . . . . . . .

256. The energy released when electron is added to a neutral gaseous atom is called.. . . . . . . . . . . . . . . . . . . . . . . . . of the atom.

257. Transition elements are chracterized by .......................... valency.

258. The most reactive member of the halogen family is ..........................

259. Bond distance is . . . . . . . . . . . . . . . . . . . . . . . . . . property.

260. In electrovalent compounds, bond distance is the .... . . . . . . . . . . . . . . . . . . . . . . of radii of. . . . . . . . . . . . . . . . . . . . . . . . . . and . . . . . . . . . . . . . . . . . . . . . . . . . .

261. In case of non-metals, .......................... is regarded as their atomic size.



262. Transition metal cations having (n - 1) d10 configuration are .......................... and. . . . . . . . . . . . . . . . . . . . . . . . . .

263. On the Pauling's electronegativity scale, the element next to F is ..........................

264. Elements of third period are known an ..........................

264 Elements having outer electronic configuration ns1 to ns2 np5 are known as. . . . . . . . . . . . . . . . . . . . . . . . . . elements.

265. The first ionization potential of boron is .......................... than that of Be.

266. The amount of energy needed to expel the most loosely bound electron from an atomis called its . . . . . . . . . . . . . . . . . . . . . . . . . .

267. The differentiating electrons enter the .......................... orbital is the case of innertransition elements.

268. On Mulliken scale, the average of ionization potential and electron affinity is knownas . . . . . . . . . . . . . . . . . . . . . . . . . .

269. One gram atomic volume of an element contains .......................... atoms.

270. The electron affinity of noble gases is ..........................

271. The vertical columns in the periodic table are known as .......................... there are.......................... groups in the long from of periodic table.

272. The size of a positive ion is than neutral parent atom because .......................... isincreased.

273. Ca 2+ ion is smaller than K+ ion because . . . . . . . . . . . . . . . . . . . . . . . . . . of Ca 2+ ion is. . . . . . . . . . . . . . . . . . . . . . . . . . than that K+.

274. Element with highest ionization potential .. . . . . . . . . . . . . . . . . . . . . . . . .

275. Most electropositive element in the periodic table ..........................

276. Lighest element in the periodic table ... . . . . . . . . . . . . . . . . . . . . . . .



277. Element with maximum electron affinity ..........................

278. Transition metal with maximum density ..........................

279. Most malleable metal ..........................

280. Element having weakest metallic bond ..........................

281. Element having highest standard oxidation potential ..........................

282. Most abundant element in the earth's crust ..........................

283. Most abundant metal in the earth's crust ..........................

284. First man made element ..........................

285. The electronic configuration of p-block element is ..........................

286. Size of atoms .......................... from left to right across a period and .......................... on descendinga group.

287. The most important contribution towards periodic classification of elements is of Scientist..........................

288. The cause of periodicity in properties is due to the reccurrence of .......................... at ..........................intervals.

289. The .......................... ionization energy of aluminium shows a sudden increase.

290. The electron affinity of fluorine is .......................... than that of chlorine and the electronegativityof fluorine is .......................... than that of chlorine.

291. Transitional metal ions having (n - 1) d1–9 configuration are generally .......................... and.......................... because of ..........................

292. An atom with high electron affinity has .......................... ionization potential.

293. Modern periodic law was given by ..........................

294. Lanthanides and actinides are .......................... block elements.



295. All the actinides are .......................... elements.

296. Atomic size of noble gas element is .......................... than its neighbouring halogen.

297. The size of anion is .......................... than neutral parent atom because .......................... charge is..........................

298. Hydrolith is a .......................... hydride.

299. The electrolysis of sodium hydride liberates .......................... gas at the ..........................

300. When hydrogen combines with lithium, it behaves like .......................... agent.

301. Hydrogen gas is liberated by the action of aluminium with concentrated solution of ..........................

302. The mass of hydrogen atom is .......................... kg.

303. The adsorption of hydrogen by palladium is commonly known as ..........................

304. Hydrogen has .......................... isotopes.

305. Ortho and para hydrogens are ..........................

306. Hydrogen is placed in 1A with .......................... and in VIIA with .......................... Hence it iscalled .......................... element.

307. From water gas, hydrogen is manufactured by .......................... process.

208. Calgon is the trade name of ..........................

309. Molecular weight of heavy water is ..........................

310. Volume percent of deuterium in heavy water is ..........................

311. Carbon monoxide combines with hydrogen when heated to 450ºC in the presence of ZnO + Cu toform ..........................

312. Electronic configuration of hydride ion is ..........................

313. Radioactive isotope of hydrogen is ..........................



314. Oxidation number of hydrogen in hydrogen peroxide is ..........................

315. Deutron contains .......................... and ..........................

316. Maximum compounds known in chemistry are of ..........................

317. Transitional elements form .......................... hydrides.

318. The maximum number of combination of water from 1H1,

1D2,

1T3, and

8O16,

8O16 and

8O18 are

..........................

319. The preparation of heavy water by the exhaustive electrolysis of ordinary water is an example of.......................... effect.

320. The ions responsible for hardness in water are .......................... and ..........................

321. In Clark process, temporary hardness of water is removed by adding a calculated amount of..........................

322. The molarity of pure water is ..........................

323. The universal solvent is .......................... (H2O / D

2O).

324. Temporary hardness of water is due to dissolved .......................... of .......................... and..........................

325. Chemical name for permutit is ..........................

326. Water containing dissolved .......................... corrodes boilers.

327. Heavy water is termed 'heavy' because it contains .......................... isotope of ..........................which is ..........................

328. Temperature of maximum density of heavy water is ..........................

329. Deuterium reacts .......................... than hydrogen.

330. Tritium is .......................... emitter.

331. Graham' salt used as water softner is ..........................

332. Temporary as well as permanent hardness of water is removed by using sodium ..........................



ANSWER KEYEXERCISE # 1

1. O2

- > F- > Na+ > Mg2 +

All the four species are isoelectronic ( 1s22s22p6). The number of positive charges in the nucleusdecreases in the order

12Mg >

11Na >

9 F >

8 O. Hence , O2- involved minimum nucleous - electrons

attraction and maximum electron - electron repulsion while Mg+2 involves maximum nucleous -electrons attraction and minimum electron repulsion .These factors make size of anion greater thanthe corresponding neutral atom and that of cation lesser than the corresponding atom.

2. Na2O

2 < MgO < ZnO < P

2O

5

Oxides of electropositive elements are alkaline while those of electronegative elements areacidic.Alkaline property will increase with increase of electropositive character of metal and acidiccharacteristics increase with increase of electronegative characteristics of normetals.Since theelectronegativity increase in the order Na < Mg < Zn < P, the acidic character of oxide will alsoincrease in the same order.

3. Na < Al < Mg < Si

The electronic configurations of given elements are

11Na 1s2 2s2 2p6 3s1

12Mg 1s2 2s2 2p6 3s2

13Al 1s2 2s2 2p6 3s2 3p1

14Si 1s2 2s2 2p6 3s2 3p2

Aluminium will have lower ionization potential than magnesium as the removal of one electron leadsto the formation of stable completely filled orbital configuration . So it is loosely held and can beremoved more easily than to remove electron from filled 3s orbital of magnesium atom.

4. N2 < O

2 < F

2 < Cl

2

Nitrogen contains triple bond, oxygen contains double bond and fluorine and chlorine contain asingle bond each. Chlorine involves bonding of 3p orbitals while fluorine involves 2p orbitals.

5. Ca+2 < Cl- < S-2 < Ar

The given species are isoelectronic. The size of cation will be the smallest. The monogegative anionwill have smaller size than the dinegative anion. The size of the noble gas Ar will be maximum.

6. HClO < HClO2 < HClO

3 < HClO

4

These acids are better represented as Cl -OH , OCl -OH , O2 Cl - OH, O

3Cl - OH.

The larger the number of oxygen atoms attached to chlorine, greater the electron pull towards oxygen,hence, more easy to remove hydrogen from the acid.



7. Hi < HBr < HCl < HF

As the size of the halogen atom increases, the strength of HX bond decreases. Besides this, decreasingper cent ionic character from HF to HI makes the bond less stable.

8. HI < I2 < ICl < HIO

4

The oxidation states of iodine in HI, I2, ICl and HIO

4 are - 1, 0 +1 and + 7, respectively.

9. HOCl < HOClO < HOClO2 < HOClO

3

The stability is explained by the increasing number of electrons involved in the formation of σ and π

bonds in going from HOCl to HOClO3. In ClO

4- ion all the valence orbitals and electrons of chlo-

rine are involved in the formation of bonds .

10. F2 < Cl

2 < O

2 < N

2

N2 involves a triple bond, O

2 involves a double bond. F

2 and Cl

2 invole a single bond each.F

2 has a

lower bond enthalpy than Cl2, This is due to more repulsion of nonbonding electrons in F

2. Besides

this, there is a possibility of multiple bonding in Cl2 involving d orbitals.

11. SiO2 < CO

2< N

2O

5 < SO

3

Increasing electronegativity of an element makes its oxide more acidic.

12. Mg2+ < Na+ < F- < O2- < N3-

See Q. 1.

13. NiO < MgO < SrO < K2O < Cs

2O

Increasing electronegativity of the element makes its oxide more basic.

14. CCl4 < MgCl

2 < AlCl

3 < SiCl

4 < PCl

5

In covalent halides , hydrolysis occurs as a result of coordination of a water molecule to the lesselectronegative element. CCl

4 does not undergo hydrolysis as carbon can not expand its octet to

accommodate water molecules.

15. S < Cl < N < O < FThe negative charge on X in HX increases with increasing electronegativity of X.This makes thehydrogen bonding more strong.

16. Cs+ < Rb+ < K+ < Na+ < Li+

The ions in solution are present as hydrated ions. The smaller the size of the ion, the greater theextent of hydration. So the size of hydrated ions becomes larger for smaller sized ion and vice versa.

17. Li+ < Na+ < K+ < Rb+ < Cs+

Li+ ion being heavily hydrated has the lowest mobility and Cs+ ion being less hydrated has the highestmobility.



18. Li < Na < K < Rb < Cs

The reactivity increases on descending the Group1.

19. Cs < Rb < K < Na < Li.

The ease of formation of hydrides decreases on descending the Group1.

20. Cs < Rb < K < Na < Li.

The melting ( or boiling ) point decreases on descending the group.

21. LiOH < NaOH < KOH < RbOH < CsOH

The basic nature of hydroxides of elements of Group1 increases on descending the group.

22. LiOH < NaOH < KOH < RbOH < CsOHThermal stability of hydroxides increases on descending the group.

23. LiCl < LiBr < LiI

The smaller sized Li+ ions polarrizes the larger anion more predominantly giving larger covalentcharacter.]

24. BeCl2 < MgCl

2 < CaCl

2< BaCl

2 < SrCl

2

25. BaCO3 < CaCO

3 < MgCO

3 < BeCO

3

On moving down the group, the lattice energies of carbonates do not decrease much while the degreeof hydration of the metal ions decreases significantly leading to decrased solubility.

26. BeF2 < MgF

2 < CaF

2 < BaF

2

Lattice energy variation is more dominating than the variation in hydration energy.

27. Be(OH)2 < Mg(OH)

2 < Ca(OH)

2 < Ba(OH)

2

Lattice energy variation is more dominating than the variation in hydration energy.

28. Be(OH)2 < Mg(OH)

2 <

Ca(OH)

2 < Ba(OH)

2

29. Ba2+ < Sr2+ < Ca2+ < Mg2+ < Be2+

The extent of hydration of ion decrases with increase in ionic size.

30. Be < Mg < Ca < Sr < BaThe reaction of alkaline earth metals becomes increasingly vigorous with increasing in atomic number.

31. Be < Mg < Ca < Sr < Ba



32. BaSO4 < SrSO

4 < CaSO

4 < MgSO

4 < BeSO

4

Hydration of ion plays a dominating role as compared to lattice energy.

33. BCl3 < AlCl

3 < GaCl

3

Increase in the electropositivity of element increases its ionic character.

34. BF3 < BCl

3 < BBr

3

Besides σ bonds between boron and halogen atoms, there exist additional pπ -pπbond between the two atoms resulting resulting from backdonation of electrons fromfluorine to boron (back bonding).

The tendency to form pπ -pπ bond is maximum in BF3 (2pπ - 2pπ back bonding) and

falls rapidly on passing to BCl3 (2pπ - 3pπ back bonding) and BBr

3 (2pπ - 4pπ back

bonding). The tendency to accept electron pair, therefore, increases from BF3 t o

BBr3.

35. InCl3 < GaCl

3 < AlCl

3

With increase in size of elements of group 13, the tendency to accept electron pair isdecreased.

36. PbCl2 < SnCl

2 < GeCl

2.

The stability of element in + II oxidation state increases on ascending the group 14.This is due to inert pair effect.

37. GeCl4 < SnCl

4 < PbCl

4

The stability of element in + IV oxidation state decreases on ascending the group14. This is due to inert pair effect.

38. Sn < Si < CThe number of hybrid orbitals and ease with which these are formed decreases fromcarbon to lead.

39. SbH3 < AsHG

3 < PH

3 < NH

3

The decrease in electronegativity and increase in size of element cause the decrease intendency to accept proton.

40. SbH3 < AsH

3 < PH

3 < NH

3

41. H3SbO

4 < H

3AsO

4 < H

3AsO

3 < HNO

3

42. H3SbO

4 < H

3AsO

4 < H

3AsO

3 < HNO

3

43. Bi < Sb < As < P < N



44. NCl3 < PCl

3 < AsCl

3 < SbCl

3 < BiCl

3

45. H2Te < H

2Se < H

2S < H

2O

46. H2S < H

2Se < H

2Te < H

2Po

47. H2O < H

2S < H

2Se < H

2T e

Largter the size of X (= O, S, Se, Te) weaker its bonds with hydrogen and moreeasily H+ gets lost in aqueous solution.

48. H2TeO

3 < H

2SeO

3 < H

2SO

3

Decreasing size and increasing electronegativity from Te to S withdraws electronsfrom O – H bond towards itself, thus, facilitating the release of proton.

49. H2TeO

3 < H

2SeO

3 < H

2SO

3

50. H2TeO

4 < H

2SeO

4 < H

2SO

4

51. H2TeO

4 < H

2SeO

4 < H

2SO

4

52. Cl > F > Br > I

53. HF < HCl < HBr < HI

54. I2 < Br

2 < Cl

2 < F

2

55. HF < HCl < HBr < HI

56. HCl < HBr < HF < HIAnomalous behaviour of HF is due to hydrogen bonding.

57. HCl < HBr < HI < HFAnomalous behavour of HF is due to hydrogen bonding.

58. HFO3 < HClO

3 < HBrO

3 < HIO

3

Ions of these acids are stabilized due to strong pπ -pπ bonding between full 2porbitals on oxygen and empty orbitals on the halogen atom. Fluorine has no d-orbitals and cannot form pπ -dπ bonds. Thus oxoacids of fluorine are not known.

59. TiCl2 < TiCl

2 < TiCl

4

Increasing oxidation state of Ti increases charge density on the metal leading toincrease in the polarization of the anionic charge cloud and thus covalency increase.



60. Zn2+ < Ti3+ < Ni2+ < Co2+ < Cr2+

Increasing number of unpaired electrons increases magnetic moment. The number ofunpaired electrons in the given species are as follows.Ti3+ one, Ni2+ two, Co2+ three, Cr2+ four and Zn2+ zero.

61. VCl4 < VCl

3 < VCl

2

Decreasing oxidation state of element increases the ionic character.

62. Fe < Cu < Na < Li

63. Al < Fe < Pb < Au

64. CO2 < B

2O

3 < BeO < Li

2O

65. As < P < S < Cl

66. O < N < F

67. O < C < S < Se

68. HOI < HOBr < HOCl

69. H2 < NH

3 < O

2 < H

2S < CO

2

Increasing molecular mass increases the density.

70. HI < HBr < HCl < HF

71. F2 < Cl

2 < O

2 < N

2

72. CaI2 < CaBr

2 < CaCl

2 < CaF

2

Increasing size of anion increases its polarization by the cation making the compoundmore covalent.

73. Te < Se < S < O

74. I < Br < Cl < F

75. B < Be < Li < Na

76. N – N < O – O < F – F



77. CsH < KH < NaH < LiH

78. LiCl > MgCl2 > BeCl

2 > AlCl

3

Hydrolysis of cations depends on two factors ; larger charge and smaller size favourmore hydrolysis, hence more free H+ (i.e. lesser pH).

79. MgO < Al2O

3 < SiO

2 < P

4O

10

80. I– < Br– < Cl– < F–

Stronger the acid, weaker its the conjugate base.

81. F– < OH– < NH2

– < CH3

–

More electronegative the atom, lesser its tendency to give a lone pair of electrons.

82. PH3 < AsH

3 < NH

3 < SbH

3

Bciling point increases with increase of molecular mass with the exception of NH3 which exhibits

hydrogen bonding.

83. B < C < O < NNitrogen has extra stability due to half-filled p orbitals.

84. BeCO3 < MgCO

3 < CaCO

3 < BaCO

3

Increasing size of cation decreases its polarizing ability towards carbonate making the compoundmore stable.

85. Ca < Al < O < N

Paramagnetism increases with increase of number of unpaired electrons.

86. LiBr < NaBr < KBr < RbBr < CsBr

The larger the difference between the electronegativities, greater the ionic character.

87. Ba2+ < Sr2+ < Ca2+ < Mg2+ < Be2+

The smaller the size, more the hydration energy.

88. AsH3 < PH

3 < NH

3

The increasing size and lower electronegativity of the central atom permit the bonding electrons to bedrawn out further, thus decreasing repulsion between bonding pairs.

89. AsF3 < PH

3 < NH

3

90. H2Se < H

2S < H

2O



91. NF3 < NCl

3

The bonding pair repulsion in NF3 is less than that in NCl

3.

92. NO2

– < NO2 < NO

2–

There is maximum repulsion between free electron(s) on nitrogen and bonding pairs.

93. NF3 < NH

3

There is lesser repulsion in bonding pairs in NF3.

94. PH3 < PF

3

The multiple bonding in P – F bond due to back bonding (involving filled p orbital on F and empty d-orbital on P) increases the electron density and electronic repulsion among the bonding electron.

95. O– < O < O+

The positive charge on atom increase its electronegativity while negative charge decreases itselectronegativity.

EXERCISE # 2

1. (a) - (f) - (b) 2. (a) - (f) - (c) 3. (a) -(d) -(c)

(b) -(c) - (f) (b) - (d) - (a) (b) - (f) - (e)

(c) - (d) - (a ) (c) - (c) - (f) (c) - (a ) - (b)

(d) - (b) - (a) (d) - (b) - (e) (d) - (e) - (f)

(e) - (a ) -(e) ( e) - (e) -(d) (e) - (c) -(a)

(f ) - (e) - (c) (f) - (a) - (b ) (f) - ( b) - (e)

4. (a) - (e ) - (c) 5. (a ) - (e) -(b) 6. (a) -(c) - (e)

(b) - (c) -(d) (b) - (f) - (a) (b) - (e) - (a)

(c) - (b) - (f) (c) - (b) - (d) (c) - (d) -(d)

(d) - (f) - (a) (d) - (a ) - (c) (d) - (b) - (f)

(e) - (a) - (b) (e) - (c) - (f) (e) - (b) - (c)

(f) - (d) - (e) (f) - (d) - (e) (f) - (d) - (b)

7. (a) - (c) - (e) 8. (a) - (d) - (f ) 9. (a) - (c) - (e)

(b) - (e ) - (c) (b) - (e) -(d) (b) - (e) - (c)

(c) - (a ) - (f) (c) - (a) - (e) (c) - (d) -(a)

(d) - (b) - (a) (d) - (b) - (a ) (d) - (b) - (f)

(e) - (d) - (b) (e) - (f ) - (c) (e) - (f) - (d)

(f) - (f ) - ( d) (f) - (c) - (b) (f) - (a) - (b)



10. (a) - (c) - (e) 11. (a) - (c) -(e) 12 . (a) - (d) - (f)

(b) - (e) - (d) (b) - (e) - (a) (b) - (e) -(f)

(c) - (a) - (f) (c) - (a) - (f) (c) - (a) -(c)

(d) - (b) - (a) (d) - (f) - (b) (d) - (b) - (e)

(e) - (f) - (b) (e) - (b) - (d) (e) - (c) -(b)

(f) - (d) -(c) (f) - (d) -(c) (f) - (f) - (a)

13. (a) - (e) - (b) 14. (a) - (c) - (e) 15.(a) - (d) -(f)

(b) - (d ) - (f) (b) - (e) - (d) (b) - (f) - (d)

(c) - (f ) - (e) (c) - (a) -(f) (c) - (a ) - (e)

(d) -(a ) - (c) (d) - (f) - (a) (d) - (b) - (c)

(e) - (c) - (a) (e) - (b) -(c) (e) - (c) - (a)

(f) - (b) - (d) (f) - (d) - (b) (f) - (e) - (b)

16. (a) - (c) - (f)

(b) - (e) - (a)

(c) - (f) - (d)

(d) - (a) - (b)

(e) - (b) - (c)

(f) - (d) - (e)



Ques 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Ans. F T T F T F T F T T T T T T T F T T F F T F T F

Ques 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

Ans. T T T T T T T F T T F T T T T T T F F T T F T F

Ques 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72

Ans. T T T F T T F T T F F T T T F F T F T T T F T T

Ques 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96

Ans. T T T T T T F F F F T F F T T T T T T T T T T T

Ques 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120

Ans. T T T T F F T F F T T F F T T T F T F T T T T T

Ques 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144

Ans. T F T T T F T T T F T T F T T T T T T T F F F T

Ques 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168

Ans. F F T T F T F F F T F T T T T T T F T T T T T T

Ques 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192

Ans. T T F T T T T T T T T F F T T T F T F F T T T T

Ques 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216

Ans. T T F F F T T T F T F T T T F T T T T T T T F T

Ques 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240

Ans. T T T T T T F T T F F T F T F T F T T T F T T T

EXERCISE # 4

Fill In The Blanks :

1. It is deliquescent 2. Efflorescence 3. Hydration 4. K[Ag(CN)2]

5. Na2CO

3 + K

2CO

3 6. NaHCO

37. 0 8. Colourless, diamagnetic

9. NaCl 10. It is highly soluble in water or it is high value of solubility product

11. Presence of solvated electrons 12. Francium 13. Iodine, Cu2I

2

14. Less 15. Impure 16. Sodium carbonate 17. Ci2S, FeS

18. Increase 19. Lithium 20. Body centred cubic 21. AgF

22. Silver 23. Thermal 24. [Cu(NH3)

4] (OH)

2 25. 1000

EXERCISE # 3



26. 100 27. Silver, volt 28. Bronze 29. Cu2O.Cu

2S

30. Four 31. Ionic, Covalent, co-ordinate 32. Na2SiO

3

33. K3[Cu(CN)

4] 34. Basic copper acetate 35. Cut off sun radiation, photosensi-

tive

36. Mercurous chloride 37. Chromyl chloride 38. Tricalcium aluminate39. sp 40. M g O

41. HgCl2, Hg

2Cl

242. Pitch blende, Mme Curie 43. 3.8ºC

44. ZnS 45. Yellow, white 46. HCl gas

47. Gypsom 2CaSO4.H

2O or CaSO

4.½H

2O 48. Mercury 49. Zinc 50. Diamagnetism

51. CaO 52. CdS 53. Anhyd. ZnCl2 + conc. HCl

54. Distillation 55. VIII group 56. Increase the plasticity

57. Lime stone, clay, gypsom 58. Hydration, evolution 59. Diakly zin

60. Dimethyl mercury 61. Impure 62. Aluminium 63. Rolled gold

64. Boranes 65. lewis acids 66. M2SO

4.M"'

2(SO

4)

3.24H

2O

67. Ammonal 68. Becomes passive 69. BF3

70. H2 gas, meta aluminate

71. Accept 72. Tetrahedral 73. Alclad 74. Cr3+

75. Ca2B

6O

11.5H

2O 76. Diborane 77. Ga 78. Acidic, Cationic

79. B3N

3H

680. Strong 81. 1800ºC 82. Diamond 83. Less

84. sp2, sp3 85. Sugar charcoal 86. 3 87. sp 88. 2

89. NaOH, Solution of Cu2Cl

290. Photosynthesis 91. Gas carbon, graphite

92. PbO2

93. Pb3O

4, HgS 94. Graphite 95. Ni, Mond's process

96. Ni(CO)4, tetrahedral 97. Tin 98. Cu and Sn



99. Solid CO2

100. Molecular 101. Non-supporter, blue 102. C O

103. Sublimation 104. Zero 105. Linear 106. Minium

107. Flint 108. HF, H2SiF

6109. Borosilicates, sodium, aluminium

110. Basic 111. Semic conductor 112. Silicon 113. Plumbago

114. SnCl4.5H

2O 115. Sodium silicate, calcium silicate 116. PbCl

2

117. Quartz 118. Hydrogen 119. Neutral, Paramagnetic 120. Linear

121. N2O

5122. Nitrogen 123. Disproportional, H

3PO

4, PH

3124. Alkali

125. Red phosphorus 126. High energy of activation 127. Fixation

128. Brown red, paramagnetic 129. One 130. Oxidising, reducing, complexing

131. Brand 132. Mono, tri 133. Fe(OH)3

134. Two 135.+ 5

136. Less 137. SbOCl 138. As2S

5139. NH

3 140. Less

141. Neutral 142. P2O

5143. Hissing, HNO

3144. Mixed

145. Norwegian salt petre 146. NO, brown, FeSO4(NO) 147. NO

3–

148. Resonance 149. NH3, NH

4OH 150. [Cu(NH

3)

4] SO

4151. N

2O 152. NO, NO

2

153. Azeotropic 154. White 155. Egg albumin 156. Phossy jaw

157. NH4NO

3158. Photochemical decomposition 159. Pyrogalol, brown

160. Cross linking 161. Oxygen 162. Allotropes 163. Sulphuric acid

164. Vandium pentoxide 165. Allotropic 166. Oleum

167. Sulphurous 168. Two, paramagnetism 169. SO2.NO

2170. Alalis, acids

171. Acid 172. Reduction, temporary 173. NaCl, O2

174. Same

175. Turpentine oil 176. Six 177. 8 178. Hypo



179. Weak H-S bond 180. SO3, S 181. Oxidised, Na

2SO

4182. S – S

183. Sodium tetrathionate184. Intermolecular H-bonding 185. D e h y d r a t i n g ,catalyst

186. Sulphur 187. C u S C N 188. Na2SO

4189. Iodine

190. Bromine 191. HF 192. Hypobromous, bromite 193. I–

194. Astatine 195. Iodine 196. Cl2

197. HBr

198. Interhalogen 199. Complex 200. Potassium tri-iodide

201. NaIO3

202. F – 203. Soluble 204. Loss of Cl2

205. Greater electropositive 206. + 6 207. Chlorine

208. Odd electron 209. KI, I2, rectified spirit 210. Dry

211. Cl2O 212. Chlorides 213. HI 214. Weakest 15. Low

216. - 1/3 217. Antichlor 218. HClO4

219. Ferrous ion

220. CO 221. Zin 222. ZnSO4.7H

2O,FeSO

4.7H

2O

223. CaO, CaSiO3

224. More 225. Reduces iondine

226. Hydrated ferric oxide 227. Pig 228. Low

229. Fe3O

4230. Colourless, diamagnetic 31. Yellow, brown, Fe(OH)

3, hydrolysis

232. 392 233. Fibrous 234. Expands 235. Redox, moisture oxygen

236. Charge to ionic radius 237. (n - 1) d, ns 238. K2MnO

4

239. [Cu(H2O)

4] ++ 240. Ten 241. FeO.Cr

2O

3242. Oxidising

243. Zr and HF 244. Osmium 245. K2Cr

2O

7246. Redox

247. Ferromagnetic 248. (n - 1) d, np 249. Wrought iron 250. Pig iron

251. Turnbull's blue, Fe3[Fe(CN)

6]

2252. + 3 and + 2 253. + 6



254. Atomic size 255. Li-Mg, Be-Al, B-Si 256. Electro affinity 257. Variable

258. Fluorine 259. Additive 260. Sum, cation, anion

261. Sing bond covalent radius 262. Colourless, diamagnetic 263. Oxygen

264. Br idge 265. Lower 266. Ionization potential 267. (n - 2), f-subshell

268. Electronegativity 269. 6.023 x 1023 270. Zero 271. group, eighteen

272. Smaller, effective nuclear charge 273. Effective nuclear charge, greater

274. Hel ium 275. Francium 276. Hydrogen 277. Chlorine

278. Osmium 279. Gold 280. Hg 281. Lithium

282. Oxygen 283. Aluminium 284. Technitium 285. ns2 np1 to ns2 np6

286. Decreasing, increasing 287. Russian, Mendeleef 288. Outer electronic configuration, regular

289. Fourth 290. Lower, higher 291. Coloured, paramagnetic, unpaired electron

292. Higher 293. Henry Mosley 294. f- 295. 5f-or radioactive

296. Greater 297. Greater, effective nuclear charge, decreased 298. Ionic or saline

299. Hydrogen, anode 300. Oxidising 301. NaOH or KOH 302. 1.6 x 10–27

303. Occlusion 304. Three 305. Allotropes 306. Alkali metals, halogens, rogue

307. Bosch 308. Sodium hexametaphosphate 309. 20 310. 66.7

311. Methyl alcohol 312. 1s2 313.1H 3 314. + 1

315. One proton, one neutron 316. Hydrogen 317. Non-stoichiometric or metallic

318. Eighteen 319. Kinetic isotope 320. Ca ++, Mg ++, Fe++ 321. Ca(OH)2

322. 55.5 323. H2O 324. Bicarbonates, calcium, magnesium

325. Hydrated sodium aluminosilicate 326. MgCl2

327. Heavy, hydrogen, deuterium

328. 11.6ºC 329. At slower rate 330. B e t a 331. Na2[Na

4(PO

3)

6]

332. Carbonate or hexa metaphosphate or aluminosilicate



ALKALI METALSSUGGEST REASONS FOR THE OBSERVATION IN FOLLOWING QUESTIONS :

Q.1 Group I elements are poor complexing agents.

Sol. The formation of complexes is favoured by (i) small size of cation, (ii) high charge,and (iii) availability of empty orbitals of low energy.

The size and charge of the alkali metals are not at all conductive to complexformation. Significant complexation is possible through chelation. The alkalimetals larger than Li exhibit higher coordination number and hence they formsome complexes.

Q.2 Alkali metal ions are diamagnetic and colourless.

Sol. Alkali metal ions are diamagnetic and colourless because the unipositive ions haveno unpaired electrons.

Q.3 Sodium metal can be used for drying ether but cannot be used for drying ethanol.

Sol. Sodium metal can be used to dry ether because it does not react with ether andremovers the water molecules. In case of alcohol, sodium reacts with alcohol toform sodium alkoxides.

Q.4 Potassium and caesium, rather than lithium and sodium are used in photoelectriccells.

Sol. K and Cs have very low ionization energies, so they can easily eject electrons evenwhen excited by visible light. This is not the case with Na and Li as they havehigher ionization energies.

Q.5 Alkali metals show characteristic colours when introduced into a bunsen flame.

Sol. When an alkali metal or its salt is heated in a flame, the valence electrons areexcited to higher energy levels. When these excited electrons fall back to theground state, the absorbed energy is given out in the form of visible light andthis gives a characteristic colour to the flame.

Q.6 The second ionization energy of alkali metals is very high as compared to the firstionization energy.

Sol. The outermost e– in the alkali metals are far from the nucleus and are shieldedby the noble gas core. So the 1st ionization energies are low. But the 2ndionization involves removing an e– from a positively charged noble gas core henceit has a large IE.

EXERCISE # 5



Q.7 Chemical reactivity of the alkali metals increase from Li to Cs.

Sol. The chemical reactivity of an element depends on the ease with which it can loseits electrons. Since the ability to lose an e– increases from Li to Cs so the reactivityalso increases from Li to Cs.

Q.8 Sodium metal is kept under kerosene oil.Sol. Na metal is very reactive. If it is exposed to air, it reacts with the oxygen, moisture

and carbon dioxide present in the air.

4Na(S) O2 → 2Na2O 2 2H O → 4NaOH 2 2CO → 2H

2O + 2Na

2CO

3

oxide hydroxide carbonate

To prevent the above reaction and protect the metal, it is kept under kerosene oil.

Q.9 A sodium fire in the laboratory is not extinguished by water.

Sol. Sodium reacts very vigorously with water and a lot of heat is given out duringthe reaction. So water is not used to extinguish sodium fire, as it will only makethe reaction more violent.

Q.10LiF is insoluble in water whereas other alkali metal fluorides are soluble.Sol. A salt is soluble if HE > LE. In case of LiF though the hydration energy is very

large (HE = – 1034), its lattice energy is even larger (LE = – 1039). All otheralkali metal fluorides are soluble. LE ∝ 1/size M+ F– as the size of the cationincreases from Li+ to Cs+ LE decreases from Li+ to Cs+. This decrease in latticeenergy increases the solubility.

Q.11Lithium has the lowest tendency to lose an electron, yet it is the strongest reducingagent.

Sol. The ionization energy cannot be taken as the sole measure of the reducing powerof an element. Ionization in gaseous state is given bySublimation L i C s

Ms(s) → M(g) 138 67Ionization

M(g) → M+(g) + e– 520 374

M(s) → M+(g) + e– 658 441which gives the impression that Li may be formed with great difficulty. But thereduction potential Eº is calculated by the following steps :

Sublimation L i C sM(s) → M(g) 138 67

IonizationM(g) → M+ + e– 520 374

Hydration

M+(g) → M(aq) – 500 – 251M(s) → M+(aq) + e– 158 190

These equations show that the high IE of Li is more than compensated by thehigh hydration energy which makes it a good reducing agent of aq. state.



Q.12Lithium is the only alkali metal to form a stable nitride (Li3N).

Sol. Due to its vary small size Li + readily combines with the small (N 3–) nitride anion.The small size of both ions gives rise to a very high lattice energy and hence astable crystal lattice.

Q.13Electrolysis of molten NaH yields H2 at the anode.

Sol. NaH is an ionic compound with the negative hydride ion (H –) present in thelattice. It is liberated at the anode (+ ve electrode) in the form of H

2(g).

Q.14The ionic conductance of alkali metal ions in aqueous solution are in the orderLi+ < Na + < K+ < Rb+ < Cs+.

Sol. The ionic conductivity of an ion in aqueous solution is inversely proportional tothe degree of hydration. As the size of the ion increases from Li → Cs the degreeof hydration decreases from Li to Cs and hence the ionic conductance increasesin the order Li+ < Na + < K+ < Rb+ < Cs+.

Q.15Among the alkali metal hydroxides, LiOH is the least soluble.Sol. In case of LiOH its high lattice energy as compared to the hydration energy is

responsible for its low solubility.

Q.16NaClO4 is less soluble than LiClO

4 in various solvents.

Sol. The lattice energy variation effect for NaClO4 and LiClO

4 is not important due

to the large size of ClO4

– ion. Therefore, it is the hydration energy difference thatdetermines the solubility in this case. As Na + is bigger than Li+ it has lowerhydration energy and hence lower solubility.

Q.17Li2SO

4 forms no alum.

Sol. Alums are double salts of the general formula M I M III (SO4)

2. 12H

2O where M1

- univalent cation, e.g. NH4

+, Na +, K+, Rb+, Cs+ and MIII - trivalent ion, e.g. Al3+,Cr3+, Fe3+. Alums generally crystallize as octahedral crystals. It has been shownthat six molecules of water surround each meta ion in an alum crystal so thatthe crystals are made up of [M(H

2O

6)]+ [M(H

2O)

6]3+ and SO

42– ions. The fact that

Li+ does not form an alum is probably because of the very small size of the Li +

ion, so that it cannot become 6 coordinate.

Q.18When burnt in air (or oxygen) Li forms the normal oxide, Na the peroxide andK the superoxide.

Sol. The tiny Li+ ion has a strongly positive field around it which on combinationswith the oxide anion (O2–) restricts the oxidation of O2– to peroxide ion (O

22–).

The positive field around Na + ion is too weak to prevent the conversion of O2–

to O2

2–; but it is strong enough to prevent the further oxidation to O2

– (super-oxide). The weak fields around larger ions of K, Rb, Cs, etc. allow the superoxideion O

2– to be formed.



Q.19From a mixture of alkali metal ions, Li + is eluted first from a cation exchanger.

Sol. The binding of cations to ion exchange resins is also dependent on cation size.The binding force being essentially electrostatic, the ion with the smallest hydratedradius will be able to approach most closely to the negative site of attachmenton the resin and will thus be held most strongly. The order of preference of thealkali metal ions is usually Li+ < Na + < K+ < Rb+ < Cs+.

Q.20LiH is more stable than NaH.

Sol. The combination of two ions both of a small size confers a high lattice energyon the crystal. Due to its very small size Li+ readily combines with H– ion to givea stable compound as compared with the large sodium ion. Also ionic covalentresonance stabilizes LiH.

Q.21Group I elements generally form ionic compounds and their salts are more solublethan those of group II elements.

Sol. The valence shell electronic configuration of alkali metals is ns 1. This suggests thatthese metals have a tendency to lose one electron and form a unipositive ion.

M → M+ + e–

Thus alkali metals form ionic compound with electronegative elements such ashalogens and oxygen. Due to the small size of the bivalent ions of alkaline earthmetals, the lattice energy of the group II metals is very high as compared to thoseof group I elements. Therefore salts of group I elements are more soluble thanthose of group II.

ALKALINE EARTH METALSQ.22Group II metals are denser than the alkali metals.Sol. The size of an alkaline earth metal is small but its atomic mass is higher than

that of an alkali metal of the same period. Therefore, the density of alkaline earthmetal is greater so the metal is denser than an alkali metal in the same period.

Q.23Group II metals are harder and have higher melting points than the group Imetals.

Sol. The alkaline earth metals are harder than the alkali metals because the densityof alkaline earth metal is higher than that of alkali metals. The hardness is alsobecause of the strong metallic bond between the atoms of alkaline earth metals.The m.p. of the alkaline earth metals are higher than those of alkali metalsbecause the metallic bonds in the crystal lattice of the group II metals are verystrong as compared to those in the crystal lattice of alkali metals. This is due tothe fact that there are two e– in the valence shell of group II metals whereas inalkali metals there is only one valence e–. Hence bonding in group II metals isstronger so more energy is required to break them.



Q.24The first ionization energy of Be is more than that of Li whereas the secondionization energy of Be is less than that of Li.

Sol. Be has 2e– in its valence shell while Li has only one e– in its valence shell.Therefore energy required to remove 1st e– (1st IE) in Be is more than that ofLi. But after the 1st e– has been removed, removing a 2nd e– from Be+ is easierthan removing it from Li +. This is because while Be + ion has still got one e– inthe valence shell, Li + ion has no e– in the valence shell so the second e– in Li+

has to be removed from a noble gas core and thus the 2nd IE of Li is greaterthan that of 2nd IE of Be.

Q.25Although the second ionization energy of alkaline earth metals is much higherthan the first ionization energy, they still form M2+ ions rather than M+ ions.

Sol. In their compounds the alkaline earth metals exist as divalent cation (M 2+) andnot as monovalent cation (M+) though the 2nd IE is greater than the 1st IE. Thisis due to the following reasons.(i) The total energy needed in the formation of a divalent cation of alkaline earthmetals is more than compensated by the energy liberated in the formation of thelattice of its compound (lattice energy).(ii) In aq. soln. the hydration energy of M2+ [M 2+(g) → M2+(aq)] is very large ascompared to the hydration energy of monovalent cation.

Q.26Group II hydroxides are weaker bases than group I hydroxides.Sol. Group II hydroxides are weaker bases than group I hydroxides because the inter-

nuclear distance at the oxygen and the metal ion is less in group II hydroxides.The increased charge density in group II metal ion also results in a strongerelectrostatic attraction between the hydroxide ion and the metal ion. This resultsin weaker dissociation of M(OH)

2.

Q.27The solubility of alkaline earth metals hydroxides in water increases from Be toB a .

Sol. In general a solid is soluble in water if the hydration energy is greater than thelattice energy. In a group both the lattice energy and hydration energy decreaseas the size of metal ion increases on descending the group. In the case ofhydroxides of group II elements with the increase in the size of cation the latticeenergy decreases more rapidly than the hydration energy. Thus the solubility ofhydroxides in water increases from Be(OH )

2 to Ba(OH)

2.

Q.28The solubility of sulphates of group II elements decreases on moving down thegroup.

Sol. On moving down the group, the lattice energy of the sulphates do not changeappreciably due to the large size of SO

42– ion. But on moving down the hydration

energy decreases to a very large extent. The solubility of group II metal sulphatestherefore decreases on going down the group.



Q.29BeO is amphoteric while other Group II oxides are basic.

Sol. Be is small in size, more electronegative and has a high IE. On descending downthe group the size increases and the electronegativity and IE both decreases. Thusthe element shows more basic character. BeO is thus amphoteric in nature andthe basicity increases as we move down the group.

Q.30Group II metal ions form stronger complexes as compared to those of Group I.Sol. Complex formation is favoured by small, highly charged ions with suitable empty

orbitals of appropriate energy. These conditions are fulfilled by group II cations.They are smaller in size than the group I cation and have double the charge (+2). The group I cations on the other hand, are too large and have a unit charge(+ 1). So group II metal ion form stronger complex.

Q.31Reduction of CaO is not possible with carbon.

Sol. Reduction of CaO is not possible with carbon because CaO is very reactive andreacts with carbon to produce carbides.

Q.32Lime water becomes turbid on passing carbon dioxide through it but becomes clearwhen more carbon dioxide is passed.

Sol. When CO2 gas is passed through lime water, milkiness (turbidity) appears due to

the formation of CaCO3.

CO2(g) + Ca(OH)

2(aq) → CaCO

3(s) + H

2O(l )

On passing more CO2 gas the insoluble CaCO

3 turns into soluble Ca(HCO

3)

2. As

a result the solution becomes clear.

CaCO3(s) + CO

2(g) + H

2O → Ca(HCO

3)

2

Q.33Anhydrite (anhydrous calcium sulphate) cannot be used as plaster of paris.Sol. Anhydrite (anhydrous CaSO

4) cannot be used as plaster of paris because it does

not set on the water and is known as 'dead burnt plaster'.

Q.34MgClO4 is an excellent drying agent.

Sol. The Mg 2+ ion in MgClO4 has a very high charge density and hence can take up

water molecules so it is an excellent drying agent.

Q.35Mg metal cannot be obtained by electrolysis of an aqueous solution of MgCl2.

Sol. In aqueous solution of MgCl2 the following ions are present : Mg2+, Cl–, H+ and

OH –. During electrolysis the species which has the higher Eº (standard electrodereduction potential) is reduced at the electrode. In this case H + has a higherpotential than Mg2+, hence H + is reduced but not Mg2+. Thus we do not get Mgmetal .

H +(aq) + e → ½H2(g); Eº = 0.00 V

Mg2+(aq) + 2e → Mg(s) ; Eº = – 2.37 V



Q.36The hydration energies of group II metal ions are Be 2+, 2455; Mg 2+, 1900; Ca 2+,1565; Sr2+, 1415; Ba 2+, 1275 kJ mol–1. How would you account for the graduallydecreasing values ?

Sol. On descending the group, the size of ions increases and hence the charge densitygoes on decreasing. Therefore the hydration energies of group II elements decreasesdown the group.

BORON FAMILYQ.37The B – X distance is shorter than what is theoretically expected in BX

3 molecules;

e.g., calculated bond length in BF3 is 152 pm whereas the observed bon length

is 130 pm.Sol. This is because of some double bond character in B – X bond in BX

3 molecule.

The double bond character arises from p π -p π back bonding between the 2porbitals of boron and np orbitals of halogens.

Q.38The first ionization energy of B is less than that of C whereas the secondionization energy of B is more than that of C.

Sol. Boron has one e– on its outermost shell while carbon has two. When the first e–

is taken out energy required in boron is less. But for 2nd IE, the 2nd e– in caseof boron is to be removed from a completely fulfilled shell whereas there is stillone e– in the outermost shell of carbon. Hence 1st IE of B is less than that ofcarbon while reverse is true for 2nd IE.

Q.39Gallium has a higher ionization energy than aluminium.Sol. Gallium has higher IE than that of aluminium because of higher effective nuclear

charge for gallium which is due to the fact that the additional 3d10 electrons donot shield the nuclear charge effectively so that the outer electrons are morestrongly held.

Q.40The increase in atomic size on moving down from Al to Tl is comparatively verylow .

Sol. This is because of the ineffective shielding of the valence e– from the nuclearcharge by the d and f electrons which results in the outer e– being more stronglyheld.

Q.41BF3 can act as a Lewis acid while CCl

4 cannot do so.

Sol. BF3 molecule act as a Lewis acid because it can accept a pair of e– from e– donor

group and thus complete its octet. But in CCl4, C atom has already got a complete

octet so it cannot accept a pair of e– and hence does not act as Lewis acid.

Q.42Boron has a high melting point

Sol. Melting point of born is very high because born has a giant three dimensionalstructure in which the boron atoms are held together by strong force of attraction.Therefore more energy is needed to break the structure.



Q.43Boron does not form B3+ ion.

Sol. The sum of the first three IE for boron is very high. Thus the total energy requiredto produce B3+ ions is much more than would be compensated by lattice energiesof ionic compounds or by hydration energy of B3+ ions in solution. So boron doesnot form B3+ ions.

Q.44Aluminium becomes passive to concentrated nitric acid.Sol. Al becomes passive to conc nitric acid due to the formation of a layer of

aluminium oxide (Al2O

3) on the surface of the metal.

Q.45Boric acid is not an acid in the Bronsted sense.

Sol. According to Bronsted theory an acid is a species that can donate protons. Boricacid B(OH)

3 is a weak acid and is more of an electron acceptor than a proton

donor.

B(OH)3 + 2H

2O = B(OH)

4– + H

3O +

Thus boric acid is not an acid in the Bronsted sense.

Q.46Molten aluminium bromide is a poor conductor of electricity.Sol. Aluminium bromide is predominantly covalent compound. Even in the molten

state there are no ions which conduct electricity.

Q.47BCl3 is monomeric while AlCl

3 is not.

Sol. The boron atom is extremely small and is unable to coordinate with the large sizedchloride ions. Hence it exits as monomer. But aluminium atom is comparativelylarge and hence the aluminium atom in AlCl

3 easily accepts a pair of electron from

the chloride atom of another AlCl3 molecule, thus completing its octet by forming

dimer.

Q.48Hydrolysis of BCl3 yields B(OH)

3 whereas NCl

3 yields NH

3.

Sol. Hydrolysis proceeds via the formation of the addition compound when watermolecule attracts the compound. In case of BCl

3 a vacant orbital on B atom

facilitates the formation of an intermediate complex and Cl is gradually replacedgiving B(OH)

3. In NCl

3 there is no vacant orbital in N atom that can accept a

lone pair of e– from water. The attraction is through the Cl atom which has avacant d-orbital and NH

3 is formed.

Q.49The p π –p π back bonding occurs in the halides of boron but not in the halidesof aluminium.

Sol. Boron is a smaller atom, it forms strong p π -p π back bonds with pure p π orbitalsof halogens. Similar π bonding is not possible in case of halides of aluminiumdue to large difference in 3p orbitals of Al.



Q.50 π -character in B – X bond in BX3 molecules decreases with increase in size of

the halogen.

Sol. This is because the tendency for the formation of p π -p π double bond is maximumin BF

3 and decreases rapidly on moving to BCl

3 and BBr

3 because the overlap

between the vacant 2p orbitals of B with higher energy 3p and 4p orbitals ofchlorine and bromine cannot take place effectively.

CARBON FAMILYQ.51The first ionization energy of carbon is more than that of boron but the reverse

is true for the second ionization energy.

Sol. The outermost electronic configuration of B is 2s 2 2p1 while that of carbon is 2s 2

2p2. Thus the energy required to remove the first electron in B is less. But forthe second IE, the electron in B has to be removed from a completely filled 2sorbital which requires a lot of energy whereas in case of carbon there is still oneelectron in p orbital which requires less energy to be removed out.

Q.52Diamond is covalent yet its melting point is very high.

Sol. In diamond, the carbon atoms are arranged in cubic closed packed pattern, i.e.they have a face centred cubic structure. Each carbon atom is sp 3 hybridized andis bound to four other C atoms. The result is a three dimensional network ofstrong covalent bonds. This causes the m.p. of diamond to be unusually high.

Q.53CCl4 does not act as Lewis acid whereas SiCl

4 and SnCl

4 can do so.

Sol. SiCl4 and SnCl

4 can act as lewis acid because of their ability to accept electrons

from donors and expand their coordination sphere. CCl4 cannot act as a lewis acid

because it cannot increase its coordination number beyond four.

Q.54In trimethylamine the nitrogen has a pyramidal geometry whereas in trisilylamineN(SiH

3)

3 it has a planar geometry.

Sol. In trisilylamine the pair of electrons occupying the p-orbital of N overlaps withthe empty d-orbital on Si which result in p π -d π bonding. Hence it has a planarstructure. Similar p π -d π bonding is impossible in (CH

3)

3N due to the absence

of d orbital in C atom. So it has a pyramidal geometry.

Q.55Elemental silicon does not form a graphite like structure as carbon does.

Sol. Carbon forms graphite like structure. In this structure each carbon in a layer iscovalently bonded to three other carbon atoms by overlap of sp2 hybrid orbitalsin a hexagonal pattern. Two adjacent layers are bonded by p electron interactions.On the other hand, Si does not form graphite like structure because.

(i) The size of Si atom is larger than that of carbon. The overlap of two 3p orbitalsresults in poor overlap and hence a weaker bond. (ii) The catenation tendency andhence to form ring structure by Si atom is very small because Si - Si bond energyis lower than C – C bond energy.



Q.56CCl4 is not hydrolysed whereas SiCl

4 is hydrolysed readily.

Sol. Due to the presence of vacant d orbital in Si atom, it can coordinate with oxygenof the water molecule so it can hydrolyse. CCl

4 is not hydrolysed because the

central atom in CCl4, i.e. carbon atom does not have vacant a d orbital.

Q.57CO2 is acidic while PbO

2 is basic.

Sol. The acidic and basic characters of oxides depend upon the metallic character. Pbis more metallic, hence PbO

2 is basic while CO

2 is acidic.

Q.58Carbon never exhibits a coordination number greater than four.

Sol. Carbon atom does not contain d orbital in its valence shell (2s22p2). Hence itcannot expand its coordinate number beyond four.

Q.59SiH4 is more reactive than CH

4.

Sol. SiH4 is more reactive than CH

4 due to the polarity of the Si – H bond and the

availability of d orbitals with silicon.

Q.60Thermal stability of Group 14 hydrides follow the order

CH4 > SiH

4 > GeH

4 > SnH

4

Sol. This is because the M-M bond energy decreases progressively as we move downfrom carbon to lead.

Q.61Pb(IV) compounds are stronger oxidizing agents than Sn(IV) compounds in acidicm e d i u m .

Sol. As we move down the group (4), + 2 oxidation state becomes more stable. So forSn, + 4 oxidation state is more stable than + 2 oxidation state while for Pb +2 is more stable than + 4. This is due to inert pair effect. Therefore Pb(IV)compounds have a tendency to get reduced to Pb(II) compounds. Thus Pb(IV)compounds are stronger oxidizing agents than Sn(IV).

Q.62Carbon acts as an abrasive as well as a lubricant.

Sol. Different allotropes of carbon have different properties. Diamond is one of thehardest substances known and hence has very good abrasive properties. Graphite,on the other hand, is soft and slippery and is a very good lubricant. Thus carboncan act as a lubricant as well as abrasive.

Q.63Silicon carbide is as hard as diamond.

Sol. Silicon carbide has a macromolecular cross-linked structure. SiC is covalentlylinked together so that every crystal represents a single gaint molecule. This is whySiC is as hard as diamond.



NITROGEN FAMILYQ.64Bond dissociation energy of N

2 > N

2+ but that of O

2 < O

2+.

Sol. Bond order of N2 is 3.0 while that of N

2+ is 2.5 hence bond dissociation energy

of N2 > N

2+. I n O

2 molecule of the 16 electrons 10 are present in bonding and

6 in antibonding orbitals, the bond order is 2.0. One of the antibonding electronis lost to give O

2+ ion; the bond order changes to 2.5 and hence the bond

dissociation energy of O2

+ > O2.

Q.65NO2 readily forms a dimer.

Sol. NO2 is the odd electron molecule (17e– N = 5 and O = 2 × 6). Hence it is very

reactive; when such reactive molecules unite the pairing of the unpaired electronon each NO

2 takes place and N – N bond of the dimer is formed.

Q.66AgCl dissolves in ammonia.

Sol. AgCl dissolves in ammonia when AgCl is added to ammonia it forms the complexion [Ag(NH

3)

2]+ in liquid NH

3 which is readily soluble. Therefore AgCl is soluble

in ammonia.

Q.67Dipole moment of NF3 = 0.2 D is less than that of NH

3 = 1.5D.

Sol. Dipole moment of NF3 is less than that of NH

3 because the lone pair of electrons

on the N atoms contributes substantially to the overall moment, reinforcing theN–H bond moment in the case of NH

3 and opposing the N–F bond moment in

case of NH3.

Q.68Nitric oxide is paramagnetic.Sol. Nitric oxide (NO) is paramagnetic owing to the presence of an unpaired electron.

Q.69Nitric oxide becomes brown when released in air.

Sol. When nitric oxide NO is released in air it becomes brown due to the formationof NO

2, nitrogen dioxide, which is a brown corrosive gas.

2NO(g) + O2(g) → 2NO

2( g )

Q.70NF3 is an exothermic compound ( ∆ H

f = – 109 kJ/mol) whereas NCl

3 is an

endothermic compound. ( ∆ Hf = + 230 kJ/mol).

Sol. NF3 is an exothermic compound whereas NCl

3 is an endothermic compound

because in case of NF3, N–F bond strength is greater than the F–F bond strength

while in case of NCl3, N–Cl bond strength is lower than the Cl–Cl bond strength.

Thus the formation of NF3 is spontaneous while energy has to be supplied during

the formation of NCl3.

Q.71On hydrolysis NCl3 yields NH

3 whereas PCl

3 yields H

3PO

3.

Sol. On hydrolysis, NCl3 yields NH

3 while PCl

3 gives H

3PO

3. This is due to the

inability of N to expand its octet due to absence of d-orbitals. The H2O molecules



are thus unable to attack the N atom. The electronegativity of N and Cl beingsimilar the H

2O molecule probably attacks the Cl atoms. Thus the three Cl atoms

are replaced by three H atoms and we get NH3 and three moles of HOCl.

Q.72NH3 is a strong base but NF

3 does not show any basic property.

Sol. NH3 is a very strong base. This is because of the lone pair of electrons on N atom

which it can donate. But, unlike the N–H bond in NH3 the N–F bond in NF

3

is highly polar due to highly electronegative F atom. So the electron density iswithdrawn from the central atom in NF

3 and it does not show any basic character.

Q.73NCl3 is readily hydrolysed whereas NF

3 is not hydrolysed.

Sol. NCl3 is readily hydrolysed due to vacant d orbitals on Cl, which can accept lone

pair of electrons from water facilitating the formation of an intermediate. In NF3

both N and F cannot accept lone pairs as both N and F do not have d-orbitals.

Q.74Nitric acid acts only as an oxidizing agent while nitrous acid can act as both anoxidizing and a reducing agent.

Sol. In nitric acid nitrogen exhibits + 5 oxidation state which is the maximum whereasin nitrous acid, nitrogen exhibits + 3 oxidation state which can be raised to +5 as well as lowered to 0. So HNO

3 can act only as an oxidizing agent while

HNO2 can act as both an oxidizing and reducing agent.

Q.75Phosphoric acid has a high viscosity (is a syrupy liquid).

Sol. Phosphoric acid H3PO

4 has a hydrogen bonding present in the concentrated

solution. So it has high viscosity and high boiling point.

Q.76Nitrous oxide supports combustion more vigorously than air.

Sol. Nitrous oxide decomposes at about 850 K yielding oxygen and nitrogen :

2N2O → 2N

2 + 2O

2

Because one third of the gas liberated is O2, N

2O supports combustion better than

air.

Q.77The 1st ionization energy of NO is less than that of N2.

Sol. In N2 there is no unpaired electron in the molecular orbital. So its first IE is high.

But in NO there is one unpaired electron in one of the π * antibonding orbitals.So this electron in the π * antibonding is easily lost to give the nitrosonium ionNO+. Hence 1st IE of NO is less than that of N

2.

Q.78Red phosphorus is denser and chemically less reactive than white phosphorus.

Sol. White phosphorus consists of P4 molecules in which P atoms are arranged at the

vertices of tetrahydrally arranged electron cloud for each P atom, three of whichare bonded to other P atom the fourth containing a nonbonding electron pair. Thetetrahedral distribution is somewhat distorted, the P–P–P bond angle being 60º.



Thus there is considerable strain in the molecule. This is why white phosphorusis highly reactive.

Red P consists of three dimensional networks formed by breaking one P–P bondin each P

4 tetrahedron and then linking the remaining P

4 unit into chains or rings

of P atoms each of which is pyramidal. This gives rise to a gaint molecularstructure. This is why red P is denser and chemically less reactive than white P.

Q.79Concentrated nitric acid turns yellow on exposure to sunlight.Sol. On exposure to light or heat nitric acid decomposes into NO

2, O

2 and H

2O. The

presence of NO2 in the partially decomposed nitric acid is responsible for its yellow

colour.

Q.80Magnetic moment of NO is temperature dependentSol. The magnetic moment of NO increases upto 520 K and remains constant above

this. Also the variation below 520 K is not in accordance with the Curie's law.The two lowest electronic energy levels of NO molecule are separated by 121 cm –

1, which is comparable with KT at normal laboratory temperature. The distribu-tion of molecules between two states of similar energy but different J values isresponsible for the anomalous variation of magnetic moment with temp.

Q.81The conductivity of AsF3 increases by the addition of KF and SbF

5 separately.

Sol. AsF3 forms complexes with both KF and SbF

5 having structures K+[AsF

4–] and

[AsF2]+ [SbF

6]– respectively. This increases the otherwise low conductivity of AsF

3.

KF + AsF3 → K+ [AsF

4] –

AsF3 + SbF

5 → [AsF

4]+ [SbF

5] –

Q.82PF3 forms numerous complexes, whereas NF

3 does not.

Sol. Both P and N in their fluorides have partial positive charge and are therefore weakLewis bases. But P due to the presence of vacant d-orbitals forms numerouscomplexes with transition metal ions containing d electrons because P-M bond hassome double bond character due to back bonding of d-electrons from metal tovacant d-orbitals of P.

Q.83The compound (CF3)

3N has no basic properties but (CH

3)

3N is a strong base.

Sol. This is due to different electronegativities of H and F. In (CH3)

3N the lone pair

on N is concentrated on N and so it can act as a donor (Lewis base). In (CF3)

3N,

the electron density on N is reduced due to the more electronegative F atom.Hence it cannot act as a Lewis base.

Q.84The oxidizing action of nitric acid can be inhibited by the presence of urea.Sol. HNO

3 acts an oxidizing agent due to traces of HNO

2 or NO

2 that is why fuming

nitric acid containing excess of NO2 is much stronger oxidizing agent. Addition

of urea consumes NO2 and thus retards the oxidizing action.



Q.85HNO3 behaves as a base in some reactions.

Sol. In the presence of a strong proton donor such as liquid HF, HNO3 behaves as

a proton acceptor (base).4HF + HNO

3 ⇔ N

3O+ + NO

2+ + 2HF–

Q.86HNO3 is an oxidizing agent but H

3PO

4 is not.

Sol. The inability of nitrogen atom to unpair and promote its 2s electron results inthe pentapositive state of nitrogen being less stable than tripositive. Thus NHO

3

where nitrogen is in + 5 oxidation state is an oxidizing agent. On the other handP has d-orbitals to expand its octet and also shows no inert pair effect, is quitestable in V state. Thus H

3PO

4 in which P is in + 5 oxidation state is not

oxidizing.

Q.87Condensed phosphates are known while condensed nitrates and arsenates are notformed.

Sol. Nitrogen and oxygen form a very stable multiple bonds because 2p π –2p π iseffective overlap and nitrate ion is stabilized by resonance. Due to bigger size ofP multiple bonds between P and O are not so strong while P–O single bond canbe stabilized by some p π –p π back bonding. Hence P prefers to form only sigmabond with oxygen and oxygen satisfies its bivalency by forming P–O–P bond andresult in the formation of condensed phosphates.

Q.88In most of the oxides of phosphorus, the P – O bond is shorter than the expectedvalue.

Sol. The shorter P–O bond distance is due to moderate d π –p π bonding involvingvacant P d π orbitals and filled p π O orbitals. The P–O bond distance is 145pm as compared with 160 pm for the sum of the single bond radii.

Q.89Pure phosphoric acid is viscous and syrupy and has an appreciable conductivity.

Sol. Pure H3PO

3 is H-bonded and hence is a viscous and syrupy liquid. The electrical

conductivity is due to self ionization.2H

3PO

4 = H

4PO

4+ + H

2PO

4–

Q.90NH3 is highly soluble in water, but its solution in water should not be called

ammonium hydroxide.

Sol. Ammonia is extremely soluble in water. It is possible to isolate two stablecrystalline hydrates at low temp NH

3.H

2O and 2NH

3.H

2O in which the NH

3 and

H2O molecules are linked by hydrogen bonds. The substances contain neither

NH4

+ and OH – ions nor discreet NH4OH molecules. Thus NH

3.H

2O has chains

of H2O linked by hydrogen bonds. These chains cross linked by NH

3 include a

three lattice by OH ... N and O ... H–N bonds. Although in aq. soln. weak baseNH

4OH is called ammonium hydroxide, there is no evidence that NH

4OH exists.

Solns of NH3 are described as NH

3 aq with the equilibrium as



NH3(aq) + H

2O = NH

4+ + OH –

K = [ ] [ ]

[ ]NH OH

NH4

3

+ −

OXYGEN FAMILY

Q.91O2 is paramagnetic whereas O

22– is diamagnetic.

Sol. Molecular oxygen is paramagnetic. According to molecular orbital theory there aretwo unpaired electrons in the π * orbitals. But in O

22– these unpaired electrons get

paired up with the result that O2

2– is diamagnetic.

Q.92O2 is inert at room temperature.

Sol. This is due to the fact that p π –p π multiple bonds are formed between O2

molecules. Oxygen molecules do not collide with sufficient force to break theirbonds at room temperature.

Q.93The O – O bond energy is less than the S – S bond energy.

Sol. Oxygen atom has two pairs of electrons in its valence shell which do not take partin bonding. These are known as non-bonding pair of electrons. In O–O bond, thesepairs of electrons are present on both the atoms and tend to repel each other. TheO–O single bond energy is low due to this repulsion. Sulphur is a bigger atomand this repulsion effect is insignificant. Hence S–S bond energy is more.

Q.94Sulphur disappears when boiled with an aqueous alkaline solution of sodiumsulphite.

Sol. Sulphur disappears when boiled with an aq. alkaline solution of sodium sulphitedue to the formation of sodium thiosulphate that is soluble in water.

Q.95SF6 has zero dipole moment but SF

4 has non-zero dipole moment.

Sol. SF6 is a symmetrical (octahedral) molecule hence the bond moments cancel each

other. SF4 molecule has a trigonal bipyramidal geometry with one position

occupied by a lone-pair. Thus the dipole moment is non-zero.

Q.96Ozone is more reactive than oxygen molecule.

Sol. Ozone is an endothermic compound, i.e. ∆ Hf is +ve. Hence it is more reactive

as it tends to convert into the more stable O2.

Q.97Sulphuric acid is viscous and has high boiling point.

Sol. The high boiling point and viscosity of sulphuric acid is due to the associationof H

2SO

4 molecules via strong H-bonding.



Q.98For dilution of H2SO

4, water should not be added to conc. H

2SO

4.

Sol. Conc. H2SO

4 has a very strong affinity for H

2O and enormous heat is evolved

in mixing. So if H2O is added to excess acid, H

2O starts boiling. Hence it is the

acid which must be added to water.

Q.99SO2 can act both as a reducing or oxidizing agent while SO

3 can function as an

oxidizing agent only and H2S as a reducing agent only.

Sol. In SO2 the oxidation state of S is + 4 which can be increased as well as decreased.

So it can act both as an oxidizing agent as well as a reducing agent. In SO3 the

oxidation state of S is + 6 which is the maximum. Hence SO3 can only act as

an oxidizing agent. In H2S the oxidation state of S is – 2 which is the minimum.

Hence it acts only as a reducing agent.

Q.100SF6 is not hydrolyzed while SF

4 is hydrolysed :

SF4 + H

2O → SOF

2 + 2HF

Sol. SF6 cannot be hydrolysed (i) S–F bond strength is very high; (ii) S atom is

coordinately saturated; (iii) it is a non-polar molecule. But in the case of SF4 there

are still empty d-orbitals present. Hence it is easily hydrolysed to SOF2.

Q.101SO3 can act as an electrophile.

Sol. The sulphur atom in SO3 has got some vacant d-orbitals which can accommodate

extra electrons. So SO3 can react with Lewis bases such as H

2O, amines and

ethers. Thus, it can act as a Lewis acid and is an electrophilic.

Q.102The bond order of S – O bond in oxyhalides of sulphur follow the trend :

SOBr2 < SOCl

2 < SOF

2.

Sol. From fluorine to chlorine and bromine electronegativity decreases. As a conse-quence the extent of p π –p π back bonding in S–O bond decreases in the sameorder giving S–O bond in SOF

2 greatest bond order. In case of SOCl

2 and SOBr

2

the Cl and Br atoms are less electronegative than oxygen. Thus the O–S p π –p π

bonding is not encouraged and bond order is less.

Q.103The compounds with S – S bond are more numerous and stable than those withO – O. Se – Se bonds.

Sol. This is due to the high bond strength and therefore high bond energy of S–S bondthan O–O, Se–Se and Te–Te bonds. S being smaller than Se and Te formsstronger covalent bonds. The S–S bond energy is more. In case of O–O bond dueto repulsion between the non-bonding pairs of e– the bond energy is low. S–S bondis stabilized by p π –d π bond which is not possible in O–O and is less effectivein Se–Se and Tl–Tl



Q.104Na2S

2O

3 made by boiling 35S with inactive Na

2SO

3 yields a precipitate of active

sulphur on acidification, but no activity remains in the SO3

2– solution.

Sol. The structure of S2O

32– is similar to SO

42–. An O atom being replaced by S on

boiling with active S 35. One S is replaced by S 35 which is precipitated onacidification. In SO

32– solution activity is lost indicating the fact that active S 35

O3

2– unit is replaced by inactive SO3

2– unit.

Q.105Why are binary compounds of oxygen and fluorine called oxygen fluorideswhereas compounds of oxygen with other halogens are called oxides. What kindof bond is expected between O and F.

Sol. In the binary compounds of oxygen and fluoride, the oxygen atom is less electrone-gative than fluorine atom. Therefore they are known as fluorides of oxygen. Withother halogens, the oxygen atom is more electronegative and hence the compoundsare known as oxides of the halogen (Cl. Br, I) concerned. The electronic configu-rations of oxygen 1s2 2s2 2p2 and fluorine 1s2 2s2 2p5 show that oxygen atom needstwo electrons to complete its octet while fluorine atom needs just one e–. Thus Oand F share e– to form a covalent bond and due to the small difference in theirelectronegativity the bond is slightly polar.

Q.106Which has the largest/smallest bond angle and why ?

Cl2O, F

2O and H

2O

Sol. Bond angle follows the order H2O > Cl

2O > F

2O because bond electron density

is max at oxygen (central atom) in case of water and min at oxygen in F2 due

to EN diff. Therefore bond closing effect of lone pairs on central atom of oxygenis min in H

2O and max in F

2O. Thus H

2O has the largest and F

2O the smallest

bond angle.

Q.107Justify that peroxymono and peroxidisulphuric acids have a peroxy linkage. Howare they structurally different from thionic acids ?

Sol. The peroxymono and peroxydisulphuric acid may be considered to have beenderived from H

2O

2 by replacing one H and both H by HSO

3 groups respectively.

H2SO

5 the monoacid and H

2S

2O

8 the peroxydisulphuric acid both on hydrolysis

yield H2O

2. Hence they contain – O – O – linkage in their molecular structure.

Q.108The process O + 2e – → O2– is endothermic, still a large number of compoundscontaining this ion exist.

Sol. The formation of O2– ion from molecular oxygen requires the expenditure of aconsiderable amount of energy ~ 1000 kJ/mol, i.e. it is endothermic

½O2(g) → O(g); ∆ H = 252 kJ/mol

O(g) + 2e– → O2–(g) ; ∆ H = 752 kJ/mol

Moreover in the formation of an ionic oxide, energy must be expended in vapor-izing and ionizing the metal atom.



M(s) ∆ ! .Hvap → M(g) I E. . → Mn+ + n e–

Nevertheless many essentially ionic oxides exist and are very stable because theenergies of lattice (LE) containing the relatively small (1.40 Å) doubly chargedoxide ion are quite high. In fact, the lattice energies are often sufficiently highto allow the ionization metal atom to unusually high oxidation.

HALOGEN FAMILYQ.109Fluorides can not be oxidized to F

2 by chemical reagents.

Sol. Fluorine is the most electronegative element. Hence when fluorine combines withanother element (X) the X–F bond strength is so high that is cannot be brokenby any chemical reagents easily. Fluorine happens to be the most powerfuloxidizing agent chemically.

Q.110I2 is more soluble in KI than in pure water.

Sol. I2 has covalent bonding and being a non-polar molecule it does not dissolve in

a polar solvent like pure H2O. On the other hand it dissolves in KI due to the

formation of triiodide ion I3

– as under :I

2 + I– = I

3–

This solution behaves as if the I2 were free.

Q.111I3

– is known but F3

– is not.Sol. F

3– ion is not known because fluorine has no vacant d-orbitals available and

therefore cannot expand its octet while iodine has vacant d-orbitals. Hence itforms I

3–.

Q.112HF is more viscous than HCl (liq.)Sol. There is a strong intermolecular hydrogen bonding between H–F molecules in

addition to dipole-dipole interaction and van der Walls interactions. But inhydrogen chloride molecules only van der Walls attraction operates. As a resultHF is more viscous and has a greater boiling point than HCl.

Q.113Molten ICl yields I2 at the cathode on electrolysis.

Sol. When molten ICl is electrolysed ionization takes place. The reaction involved is3ICl = I+ + [ICl

2] –

Thus, the reduction of the cation to form (I +) takes place at the cathode formingI

2

2I2

+ + 2e = I2

Q.114Iodine does not form compounds with Xe.Sol. The compounds of Xe are formed by the promotion of p-orbitals to d-orbitals. But

iodine being a very large molecule having a low electronegativity is not able toactivate the outer e– and promote them to d-orbitals. Hence I

2 does not form X

compounds with Xe.



Q.115HF is a weak acid despite the fact that F is the most electronegative element.Sol. HF is a weak acid even though fluorine is the most electronegative element

because F– is not a stable molecule due to very small size of fluorine and highelectron density so produced after the removal of H +.

Q.116HF is stored in wax-coated bottles.Sol. HF is stored in wax-coated bottles because it reacts with silica of glass to give

water soluble acid H2SiF

6.

SiO2 + 4HF → SiF

4 + 2H

2O

SiF4 + 2HF → H

2SiF

6

Q.117The brown colour of an acidified dilute solution of iodine in aqueous KI isintensified by the addition of a nitrite but is discharged by the addition ofsulphite.

Sol. On the addition of a nitrite (NO2

–) I– is oxidized to I2 in turn the colour of the

solution is intensified. The addition of sulphite (SO3

2–) consumes I2 which oxidizes

sulphite to sulphate (free I2 is reduced to I–) hence the colour is discharged.

Q.118KHF2 is known but KHCl

2 or KHBr

2 are not.

Sol. KHCl2 and KHBr

2 are not known due to the stearic hindrance offered by the large

chlorine and bromine atoms as compared to the small fluorine atom in KHF2.

Q.119HCl is covalent but its aqueous solution is conducting.Sol. This is because HCl is a strong acid and on dissolution in water it dissociates

completely forming H + and Cl– ions. It is these ions that help in electricalconductance.

Q.120The acid dissociation constant of HF is very low in dilute solution, but iscomparatively higher in more concentrated solution.

Sol. Consider the equilibriumHF + H

2O = H

3O+ + F–

Due to the high bond dissociation energy of HF, it is a weak acid. But inconcentrated solution F– forms a complex, HF

2– with HF thereby shifting the

equilibrium to the right. This increases the conc of H3O+ and hence the pKa value

increases.

Q.121The non-existence of Cl+ ion even though the ionization potential of Cl is lessthan that of hydrogen.

Sol. H+ is formed due to the high hydration energy of hydrogen which compensatesfor the high IE.

Q.122Solution of I2 in benzene and CCl

4 are purple while in solvents such as ketones

and ethers have a brown colour.

Sol. Purple or violet colour of the solution of iodine is due to the separation of thedissolved iodine (solid) in I

2 molecules, i.e. weak van der Wall's forces which are



present in solid iodine are broken and as I2 molecules are violet in colour the

solution is violet. In case of benzene the formation of weak complexes of I2 with

unsaturated molecules takes place, thus giving charge transfer complexes. In thisprocess adsorption of colour takes place which gives pinkish brown colour as thecomplementary colour.

NOBLE GASES

Q.123Xe forms compounds with F whereas Ne does not.

Sol. Ne does not form compounds with F like Xe does because the IE of Ne is muchhigher than that of xenon.

Q.124Boiling point increases from He to Rn.

Sol. The boiling point of noble gases increases with increase in atomic number becausethere is an increase in the van der Walls forces with increase in size and atomicmass .

Q.125Deep sea divers now a days use a mixture of He(80%) and O2 (20%) in their

breathing apparatus instead of air (80% N2, 20% O

2).

Sol. We know that as pressure increases the dissolutions of a gas increases. Under highpressure below the sea a lot of N

2 from the 80-20 : N

2 – N

2 mixture gets dissolved

in the blood and on coming to the surface at lower pressure this dissolved nitrogenleaves the blood in a painful way. (The pairs being called bonds).

To avoid this pain sea divers use a 30-20 mixture of He and O2 because He at

high pressure is less soluble in blood as compared to N2 and hence the bubbling

out on the surface is less painful.

Q.126The solubility of noble gases, in water, increases on going down the group.

Sol. As the size increases from He → Xe the ease of polarization of the atom alsoincreases from He → Xe. This is why the solubility in water increases down thegroup.

Q.127Fluorine forms compounds with Xe but not with He.Sol. Fluorine forms compounds with Xe because the ionization energy of Xe is less and

there are vacant d-orbitals available. But in case of He there are no vacant d-orbitals present and its ionization energy is very high. So fluorine does not formcompounds with He.

IIT - JEE · VISION 2000 CHEMISTRY 1 IIT JEE INORGANIC CHEMISTRY ALKALI METALS F The alkali metal...

Documents

Transcript of IIT - JEE · VISION 2000 CHEMISTRY 1 IIT JEE INORGANIC CHEMISTRY ALKALI METALS F The alkali metal...