CHEMISTRY FOR

CLASSES VII TO X

CONTENTS

Page No.1. Class X 2

2. Class IX 23

3. Class VIII 34

4. Class VII 50

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CLASS - X

ATOMIC STRUCTURE

Rutherford’s Planetary model based on X-ray scattering experiment :(i) Atoms are spherical in shape and mostly hollow.(ii) The nucleus is made up of protons and neutrons and the mass of the atom

is almost due to its nucleus.(iii) Electrons revolve around the nucleus, like planets around the sun.(iv) Two types of forces are present in the atom. (i) The force of attraction between

the electrons and the nucleus. This force pulls the electrons towards thenucleus. (ii) The revolving electrons experience a centrifugal force directedaway from the moving path of electrons. This force pulls electrons awayfrom the nucleus. The two forces are equal and opposite. Thus the atom isstable.Defects of Rutherford’s model :

(i) According to classical laws of physics a moving particle should lose energyand come closer to the nucleus. If it loses energy, it eventually should fallinto the nucleus and the atom should collapse. But atoms are stable.

(ii) If the electron loses energy continuously, the atomic spectra should consistof continuous bands. Experiementally, atomic spectra are made up of discretespectral lines.Bohr’s model of atom : Bohr’s theory is based on Planck’s quantum theoryof radiation. Bohr retained the atomic model of Rutherford and proposedthe following postulates :

(i) Electrons are moving with high velocity around the nucleus in specified pathscalled “orbits or shells”. As long as the electron is in a particular orbit itsenergy is constant. There fore these orbits are called “Stationary orbits orstationary shells”.

(ii) Each stationary orbit corresponds to a definite energy. These stationaryorbits are designated by K,L,M,N,O...... . The orbit close to the nucleus hasless energy compared to the orbit away from the nucleus. .

(iii) When an electron jumps from a higher energy orbit (outer orbit) to a lowerenergy orbit (inner orbit), the difference in energy is emitted as radiation.E2-E1 = hVwhere E2 and E1 are energies of outer and inner orbits respectively, v is thefrequency of radiation and h is Planck’s constant.

(iv) The angular momentum (mvr) of the electron revolving in a stationary orbit

is equal to integral multiples of Π2h

Angular momentum, mvr = nh/2 Π

where ‘n’ is an integer (n = 1,2,3,4...)

m = mass of electronv = velocity of electronr = radius of circular orbith = Planck’s constant.Limitations of Bohr’s atomic theory:

(i) Bohr’s theory could not explain the atomic spectra of higher elements suchas He. Li, Be, B, C, ............. which have more than one electron.

(ii) Zeeman Effect : The atomic spectral lines, in the presence of applied magneticfield, split into several lines (fine spectrum). This phenomenon is called“Zeeman Effect”. Bohr’s model could not account for the Zeeman effect.

(iii) Bohr’s model could not justify the quantization of angular momentum. Whyshould angular momentum be quantized and be equal to nh/ Π2 (n = 1, 2, 3........)?

(iv) Bohr’s theory could not account for the formation of chemical bonds.Principal Quantum Number (n) : Neils Bohr proposed this quantum number.It is designated as “n” and can take only integer values such as 1,2,3 ..... etc.Principal quantum number gives the size and energy of the stationary orbit.As the ‘n’ value increases, the size and energy of the orbit also increases.The number of ‘sub energy levels’ (sub stationary states in a given shell) isequal to n2.Azimuthal Quantum Number (l) : Sommerfeld proposed azimuthal quantumnumber and is designated as “l”, l can take values 0, 1, 2, 3... (n-1). l givesinformation regarding the shape of sub-stationary state or sub-shell.Magnetic Quantum Number (m or m1): Magnetic quantum number isproposed by Lande and is designated as ‘m’. The value of m depends on thevalue of l. For l=3, m can take up 7 values, viz. -3, -2, -1, 0, +1, +2, +3. ‘m’gives information regarding orientation of orbitals in the presence of magneticfield.Spin Quantum Number (s) : Uhlenbeck and Goudsmit suggested that amoving electron in an orbit revolves or spins on its own axis. The electroncan spin clockwise or anti clockwie and this is represented ↑ as and↓ respectively.

Spin quantum no. can take only + 21

or - 21

values.

Atomic Orbitals : Atomic orbital is defined as the region in space wherethere is a finite probability of finding the electron.s Orbitals : s orbital is sphericalp Orbitals : They are dumb-bell shaped.d Orbitals : The d orbitals correspond to l=2, They are double - dumb bellshaped.Max Planck proposed quantum theory of radiation energy E=h ν where h iscalled planck’s constant and is equal to 6.625x10-27 erg.sec.

Sommerfeld’s elliptical model :(i) Each stationary state is divided into sub-stationary states or sub-levels.(ii) Stationary state is indicated by principal quantum number ‘n’ and sub-

stationary states by azimuthal quantum number l.(iii) The number of sub-stationary states in a given stationary state is dependent

on the value of ‘n’.(iv) n=1 (K-shell) has one, n=2 (L-shell) has two, n=3 (M-shell) has three .... sub-

stationary states.(v) In the presence of magnetic field, the sub-stationary states split into groups

of states.(vi) The principal quantum number n can take values 1, 2, 3, 4....(vii) Principal quantum number gives the size and energy of stationary orbits.(viii) Azimuthal quantum number (l) gives the shape of sub-shell or orbital.(ix) The maximum value of l is (n-1).

Aufbau Pricipal : Aufbau principal states that electron occupies the orbitalhaving the least energy.An electron occupies an orbital whose (n+1) value is minimum. If (n+1)value is same for two orbitals, it occupies the orbital having less ‘n’ value.Degenerate orbitals : Orbitals having same energy are called ‘degenerate’orbitals.Hund’s rule : It States that pairing of electrons takes place when all theavailable degenerate orbitals are occupied by one electron each.Pauli exclusion principle : It states that no two electrons will have all thefour quantum numbers same.The physical quantities of atom are : (i) atomic radius, (ii) ionizationpotenial, (iii) electron affinity, (iv) electropositive nature and (v) oxidizing andreducing properties.Atomic radius : It is the distance between the nucleus and outermost orbital.It is expressed in A0 (Angstrom) units. 1A0=10-8cm.Ionization potential (I.P) : It is the minimum energy required to remove anelectron from outermost orbital in the gaseous state.Units of I.P. are eV or K.J.mol-1 or k. cal mol-I.

I.P. is dependent on (i) nuclear charge, (ii) size of the atom and (iii) charge ofthe ion.Electron affinity (EA) : Electron affinity is the energy released when anelectron is added to a neutral gaseous atom in the ground state.Units of EA are eV or K.cal.mol-1.

CHEMICAL BOND

Octet Configuration: The filling up of valence orbital with 8 electrons isreferred to as octet configuration.Electrovalent Bond : Complete transfer of one or more electrons from oneatom to another will lead to the formation of ionic or electrovalent bond.Covalent Bond : Sharing of electrons will lead to the formation of covalentbond.The energy of the molecule is less than the sum of the energies of atomspresent in the molecule.Covalent bond is formed by the overlap of two pure atomic or two hybridizedor one hybridized and one atomic orbital.Strong bond is formed by the maximum overlap of orbitals.End-on-end overlap of orbitals lead to the formation of sigma ( σ ) bond andpartial overlap of orbitals lead to the formation of pi(Π )bond.Sigma ( σ ) bond is stronger than pi( Π )bond.Sigma bond exists independently.pi bond has no independent existence. It exists only in the presence of asigma bond.In a double bond one sigma and one Π bond are present.In a triple bond one sigma and two Π bonds are present.p-p overlap is present in F2, Cl2, Br2 and I2.s-p overlap is present in HF, HCl, HBr and HI.Molecules having single bonds have only σ bonds.Molecules having single bond are H2, F2, Cl2, Br2, I2, BeCl2 et.Molecules having double bond are O2, ethylene (C2H4). CO2 etc.Acetylene(C2H2), nitrogen (N2), HCN, CaC2 etc., have triple bonds.In coordinate covalent bond, both the electrons are supplied by one atom.Examples of coordinate covalent bond are F3B-NH3, NH4+, H3O+ etc.CO2, BeCl2, and HCN have linear structures.Water molecule has “V” shape.NH3, PCl3 and PH3 have pyramidal shape.PCl5 and has trigonal bipyramidal structure.

PERIODIC CLASSIFICATION OF ELEMENTS

Mendeleef’s periodic law may be stated as follows :The properties of elements are the periodic functions of their atomic weights.Modern Periodic Law : The properties of the elements are periodic functionsof their atomic numbers.Atomic Number : The atomic number corresponds to the number of positivecharges on the nucleus and also to the number of electrons in the extranuclear structure.Based on the electronic configuration, the elements are classified into fourclasses : inert gases, representative elements, transition elements and innertransition elements.Inert Gases : Gases such as He, Ne, AR, Kr, Xe and Rn are generally inerttowards any chemical reactions and hence named as “inert gases”.Their outermost electronic configuration is ns2 np6. Except helium whoseelctronic fonfiguration is Is2.Representative elements : Elements having incompletely filled outermost(valence)shell are known as ‘representative elements’. These elements havethe general electronic configuration from ns1 to ns2 np5 where ‘n’ is principalquantum number.s-block elements : Elements having ns1 and ns2 as their outermost electronicconfiguration are known as ‘s-block’ elements. Group IA and IIA fall intothis block.p-block elements : These elements have ns2np1 to ns2np5 as their outermostelectronic configuration Elements belonging to IIIA, IVA, VA, VIA and VIIAare known as ‘p-block elements.Atomic Radius : “Atomic radius is defined as the distance between thecentre of the nucleus and the outermost orbital”.Ionization Energy (IE) or Ionization Potential (IP) : “lonization energy isdefined as the minimum energy required to remove an electron from theoutermost orbital of an atom in the gaseous state”.In a group, the ionization energy decreases from top to bottom.Electronegativity (EN) : It is defined as the tendency of bonded atom in amolecule to attract the electron density of the shared pair of electrons.In a period, the electronegativity increases due to the decrease in size of theatom. In a group the electronegativity decreases due to increase in atomicsize.Electropositive character : Electropositive character is ability to loseelectrons and become positively charged ions. The elements present on theleft side of periodic table (GROUP I and II) are more electropositive thanothers.Oxidation : Addition of oxygen to a given compound or removal of hydrogenfrom a given compound is called Oxidation.

Reduction : Removal of Oxygen or addition of hydrogen to a given compoundis known as reduction.Reducing Reagent: The reagent used to reduce the given compound iscalled reducing reagent.Oxidizing reagent : The reagent used to oxidize a given compound is calledoxidizing reagent.In a period from left to right the reducing property decreases and oxidizingproperty increases. In a group the reducing property increases and oxidizingproperty decreases.

ALKALINE EARTH METALS

Group IIA metals are often called alkaline earth metals.Atomic Size : Atomic size increases as we go from Be (Beryllium) to Ra(Radium).Ionization Enegry : Ionization energy can be expressed in kJ/mole or electronvolt (eV). Ionization energy of these metals decreases as we go down in theperodic table from beryllium to radium.Electronegativity : The electronegativity of group IIA elements decreasesfrom Be to Ra due to increase in atomic size.Melting and Boiling points : The melting and boiling points of group IIAelements are higher than alkali metals.Alkaline Earth Metals : Group IIA elements are called alkaline earth metals.These elements react with (i) water to liberate hydrogen (ii) oxygen to formoxides (iii) Hydrogen to from hydrides and (iv) Chlorine to form chlorides.Oxides of these elements show basic character.All group IIA elements form hydrides of type MH2, which act as reducingreagents.BeCl2 is covalent. Other halides are ionic.Group IIA elements are extracted from their chlorides by electroysis reduction.KCL and NaCl are added to anhydrous MgCl2 during the electrolysis to reducethe melting temperature and increase the electrical conductivity.Graphite rod and iron pot act as anode and cathode respectively during theelectrolysis of MgCl2.

SOLUTIONS

Solution : A homogeneous mixture containing two or more substances iscalled solution.Solute : The component which is relatively less in quantity is called solute.Solvent : The component which is comparitively large in quantity is calledsolvent.In an aqueous solution, the solvent is water.Solubility : It is defined as the maximum amount of the solute by weight ingrams dissolved in 100gms of solvent of constant temperature.“Solutions are divided into (i) unsaturated (ii) saturated and (iii)supersaturated solutions based on the solubility of the solute.Saturated solution : A solution which remains in contact with excess ofsolute is said to be a saturated solution.Unstaturated solution : A solution in which it is possible to add more soluteto continue to give a homogeneous solution.Supersaturated Solution : The solution in which solute present is morethan in the saturated solution.Solubility of a compound in a given solvent depends on (i) the nature of thesolute and the solvent and (ii) temperature.Weight Percentage : “The weight of solute (in grams) present in 100 gramsof solution is called weight percentage”.

Weight percentage = 100xWw

w+

where w = grams of soluteW = grams of solvent.Volume Percentage (V%) : The volume of solute (in ml) present in 100 ml ofsolution is called “Volume percentage”.

V% = 100xVv

v+

Where v = ml. of soluteV = ml of solventMolarity : Molarity is defined as the number of moles (or gram moles) of asolute present in one litre of solution. It is represented by the symbol “M”.

Molarity = V1x

wt.mol.gmw

(V in litres)

where W = wieight of solute.V = volume of solution.Mole fraction : Mole fraction is defined as the ratio of number of moles ofconsituent to the total number of moles of all constituents present in thesolution.

w%, V% and Mole fraction have no units.The units of molarity are mol.lit-1 Molarity depends on temperature. Molefraction is independent of temperature.Strong Electrolytes : Some substances such as NaCl, NaNo3, Na2So4, KCl,KNO3, FeCl3, BaCl2, etc. when dissolved in water dissociate into ions. Thesesubstances are known as “strong electrolytes”. They let current pass throughtheir solutions.Weak Electrolytes : Some substances like CH3, COOH, NH4OH etc. whendissolved in water dissociate incompletely. They are called Weak Electrolytes”.The extent of dissociation increases with increases in temperature anddilution.Non-Electrolytes : Some other substances such as sucrose, glucose, ureaetc., when dissolved in water do not dissociate. They do not allow current topass through their solutions.

ACIDS, BASES AND SALTS

Preparation of Acids : Acids are formed when non-metallic oxides aredissolved in water.SO2 + H2O → H2SO3

(Sulphur (Sulphurousdioxide) acid)Preparation of bases : Bases are formed when metallic oxides are dissolvedin water.Na2O + H2O → 2 NaOH(Sodium (Sodiumoxide) hydroxide)Properties of Acids :

(i) Acids change the colour of the indicators. Blue colour of litmus paper ischanged to red. Orange colour of methly orange indicator is changed to red.

(ii) Acids liberate hydrogen gas by reacting with metals like Zn, Mg etc.

2HCL + Mg → MgCl2 + H2 ↑

(iii) Acids react with bases to form salt and water.HNO3 + KOH → KNO3 + H2O

(iv) Acids react with metallic oxides to form salt and water.2HNO3 + ZnO → Zn(NO3)2 + H2O

(v) Acids liberate carbon dioxide by reacting with carbonates and bicarbonates.NaHCO3 + HCl → NaCl + CO2 + H2O

(vi) Aqueous solutions of acids show electrical conductivity.Properties of Bases :

(i) Bases, like acids, change the colour of indicators. Red colour of the litmuspaper is changed to blue. The orange colour of the methyl orange solution ischanged to yellow.

(ii) On heating bases decompose into metal oxides and water2 Fe(OH)3 → Fe2O3 + 3 H2O

(iii) Bases react with acids to form salt and water.Ca(OH)2 + 2HCl → CaCl2 + 2H2O

(iv) Aqueous solutions of bases also show electrical conductivity.Arrhenius theory : According to Arrhenius theory acids produce H+ ionsand bases produce OH- ions in aqueous media.Limitations of Arrhenius theory :

(i) This theory explains the nature of substances which are soluble in wateronly.

(ii) Arrhenius theory fails to explain the acidic nature of some substances likeCO2, SO2, SO3 and P2O5 etc., which do not have H+ ions of their own.

Ionisation of Water : Water ionises to a small extent and produces H+ andOH- ions.The ionisation is temperature dependent.Ionic product of water : The product of concentrations of H+ and OH- ionsin one mole of water is defined as the ionic product of water.It is represented by KW.ionic product, KW = (H+) x (OH-)The KW is temperatue dependent. The value of KW increases with increase intemperature as ionisation increases.KW remains constant even after addition of an acid or a base.

pH = -log10(H+)

For acidic solution the (H+) > 10-7

For neutral solution the (H+) = 10-7

For basic solution the (H+) < 10-7

pH of some common fluidsSl.No. Sample pH1. Gastric Juice in the

stomach 1-22. Lemon juice 2.43. Urine 4.8 - 7.54. Aerated Water 5.55. Saliva 6.4 - 6.96. Pure water 77. Blood 7.32 - 7.45

Neutralisation : Combination of H+ and OH- ions is called neutralisation.Heat of Neutralization : The heat liberated when one mole of strong acid orH+ ions react with one mole of strong base or OH- ions is called heat ofneutralization.Strong Acids / Bases : Completely ionized acids and bases are called strongacids and strong bases respectively.Weak Acids / Bases : Incompletely ionized acids and bases are called weakacids and weak bases respectively.For a reaction between strong acid and strong base the heat of neutralizationis 13.7 k.cal.mol-1.For a reaction involving weak acid or weak base, the heat of neutralization isless than 13.7 k.cal.mol-1.

CHEMISTRY OF CARBON COMPOUNDS

Allotropy : The occurrence of same element in two or more different forms isknown as allotropy.Carbon has two important allotropic forms, viz., diamond and graphite.Diamond : Diamond is a crystalline solid. It is the costliest and one of thehardest materials. It has a density of 3.51 gm./cc. It is insoluble in anysolvent and a bad conductor of heat and electricity. It remains unaffectedby acids and bases. Due to its hardness it is used as glass-cutter.Structure of Diamond : In diamond carbon atoms are in tetrahedralarrangement. C-C bond length is 1.54 A0 and bond angle is 1090281.Graphite : It is a grayish-black soft crystalline solid with metallic lustre andsoapy to touch. So it is used as a lubricant. It is a good conductor of heatand electricity. It is insoluble in any solvent. It has much less density thandiamond viz., 2.25 gm. c.c.Structure of Graphite : Graphite contains carbon atoms in hexagonal ringsand the rings in turn are joined together to form a layer.C60 (buckminster fullerene) : C60 is an allotropic form of carbon. It has afootball like structure made up of carbon atoms. C60 contains 60 carbonatoms arranged in 32 rings. It is hollow inside. The average bond length is1.4A0.OXIDES OF CARBON :Carbon forms two types of oxides. They are carbon monoxide (CO) and carbondioxide (CO2).Carbon Monoxide (CO) : It is a poisonous gas mainly found in exhaustfumes of industry and automobiles.Carbon Dioxide (CO2) : Carbon dioxide is present in air to the extent ofabout 0.03% by volume. It is a product of combustion, respiration andfermentation reactions.Methods of preparation of CO2 :

(i) By heating carbon in excess of oxygen.C + O2 → CO2

(ii) By heating metallic carbonates and bicarbonates.Ca(HCO3)2 → CaCO3 + H2O + CO2

(iii) By the action of acids on carbonates or bicarbonates.CaCO3+2HCl → CaCl2+ H2O + CO2

(iv) Carbon dioxide is obtained as a byproduct in the manufacture of alcohol byfermentation of sugar.Physical properties of CO2 :

(i) It is a colourless gas with faint pungent odour and slight acidic taste(ii) It is heavier than air.

(iii) It is soluble in water.(iv) Carbon dioxide is not poisonous, but it does not support life. Its harmful

effects to life are due to suffocation.Chemical properties of CO2 :

(i) It is highly stable.(ii) It is neither combustible nor a supporter of combustion.(iii) It dissolves in water to give carbonic acid, H2CO3. Thus it is also known as

anhydride of carbonic acid.CO2 + H2O → H2CO3

(iv) Due to its acidic nature it turns blue litmus into faint red and neutralizesalkalies to form of carbonic acid.

CO2 + 2NaOH → Na2CO3 + H2O(v) When CO2 is passed through lime water a milky white precipitate is formed

due to the formation of CaCO3.

Ca(OH)2 + CO2 → CaCO3 ↓ + H2O

Photosynthesis : Photosynthesis is a phenomenon in which green pigmentof the plants prepares the starchy food materials by combining CO2 andwater in the presence of sunlight. Oxygen is evolved in the course of thisprocess.

6CO2+6H2O → 6O2+C6H12O6 (glucose)Uses :

(i) Carbon dioxide is used in the preparation of soda water, cool drinks (aeratedwater) etc.

(ii) It is used in the manufacture of washing soda, Na2CO3.(iii) It is used as fire extinguisher.

Dry Ice : The solid carbon dioxide is called dry ice.Unique Properties of Carbon :

(i) Catenation : Catenation is the phenomenon in which atoms of same elementjoin together to form long chains.

(ii) Isomerism : Compounds having same molecular formula but differentstructures are called isomers and the phenomenon is called isomerism.

(iii) Formation of multiple bonds : Carbon atoms are capable of forming multiplebonds with other carbon atoms.Sources of Carbon Compound : The principal natural resources for carboncompounds are plants, and carbonaceous materials like wood, natural gas,coal, petroleum etc.ALKANES / PARAFFINS :Saturated Hydrocarbons are also called paraffins. They have the generalformula CnH2n+2.Properites of Alkanes :

(i) Alkanes are highly unreactive because they are saturated.(ii) Alkanes are used as fuels.

Alkenes : Alkenes are unsaturated hydrocarbons having their general formulaCnH2n. Alkenes are also known as olefins.Properties of alkenes :

(i) Due to the presence of double bonds they undergo addition reactions givingrise to saturated compounds.

(ii) Alkenes are used in production of polymers.Alkynes : They are unsaturated hydrocarbons with the general formula CnH2n-

2 where n=2,3,4...etc.Properties of alkynes ;

(i). Alkynes are colourless and odourless.(ii) They are insoluble in water.(iii) On combustion they produce large amount of heat. Hence these are also

used as fuels.Distillation of petroleum gives varities of carbon compounds.Dry distillation of coal gives many important carbon compounds.The compounds of carbon and hydrogen are called hydrocarbons.Hydrocarbons are classified into saturated and unsaturated hydrocarbonds.Alkanes are saturated hydrocarbons.Unsaturated Hydrocarbons contain one or more double or triple bondsbetween carbon atoms.Alkenes, alkynes and benzene are unsaturated hydrocarbons.Some unsaturated hydrocarbons undergo polymerization.Functional Group : A group of atoms in carbon compound showingcharacterestic properties is called functional group.Alcohol (-OH), aldehyde (-CHO), Ketone (>C=O), acid (-COOH), ester (-COOR)and amine (-NH2) are some important functional groups.

CARBOHYDRATES AND PROTEINS

Carbohydrates : The polyhydroxy aldehydes or ketones are calledcarbohydrates.Carbohydrates can be classified in many ways.They are classified as monosaccharides, disaccharides and polysaccharidesbased on the number of monomer units present in carbohydrates.Glucose, fructose and mannose are examples of monosaccharides.Sucrose, maltose and raffinose are examples of oligosaccharides.Starch and cellulose are examples of polysaccharides.Glucose :

(i) Glucose is prepared by plants by a process known as photosynthesis.(ii) Glucose give energy to the living cells.(iii) Glucose can be tested by Tollen’s and Benedict’s reagent.

Starch is tested by iodine solution.Preparation of Sugar :

(i) Sugar is manufactured from sugar-cane.(ii) Canes are crushed to obtain juice.(iii) Juice is purified by defecation, carbonation and sulphitation.(iv) Juice is concentrated by evaporation of water.(v) Crystals of sugar formed by supersaturation of juice are separated in

centrifuges.Preparation of Alcohol : Alcohol is manufactured from molasses byfermentation.Fermentation : It is the breakdown of large molecules by microorganisms.Molases is fermented by yeast.Yeast produce two enzymes, invertase and zymase.Alcohol is useful in industries as solvent.CO2 is a byproduct of alcohol industry.Amino Acids :The general formula of amino-acids is

H|

R - C -COOH|

NH2

where R is a group that differs from one amino-acid to the other.

Names and formula of R group of some amino-acids.Name Formula of R AbbreviationGlycine H GlyAlanine CH3 AlaValine (CH3)2 CH ValCysteine CH3-SH CysTreonine CH3CHOH ThrePhenylalanine C6H5CH2 PheSerine CH2OH SerLeucine (CH3)2-CH-Ch2

Amino acids have salt like or zwitterionic structure.Amino acids are building blocks of proteins.They are either synthesized in the living body or taken through diet.Human body cannot synthesize certain amino acids called essential aminoacids.There are nine essential amino acids and they must be supplied throughdiet only.Proteins:Proteins are formed from amino-acids.Proteins are polymeric compounds of amino acids.Peptide bond : The -CO-NH-bond is called peptide bond. If two amino acidsjoin, the resultant product is called dipeptide.Haemoglobin : Haemoglobin is a protein responsible for carrying oxygen inthe blood. It consists of 574 amino-acids and change of even one amino-acid in the sequence produces ineffective haemoglobin called ‘sickle cellhaemoglobin’. This causes a disease called sickle cell anaemia.Normal haemoglobin : -Val-His-Leu-Thr-Pro-Glu-Glu-Lys.Sickle cell haemoglobin : -Val-His-Leu-Thr-Pro-Val-Glu-Lus.Functions of Proteins :

(i) Proteins serve as the chief structural material of animal tissues.(ii) Some proteins function as enzymes and they catalyze biological reactions.(iii) They regulate metabolic processes.(iv) Some proteins act as anti-bodies. They protect the body from the disease

causing germs.

OILS AND FATS

Oils and fats are the triesters of glycerol with fatty acids.Lauric, stearic, oleic and linoleic acids are some examples of fatty acids.Oil is the substance that exists in liquid state at room temperature and fatexists in solid state.Unsaturated Oil : Certain oils contain fatty acids with one or more C=Cdouble bonds.The unsaturated oils can be converted to saturated oils by hydrogenation.Hydrogenation of oils give fats.Dalda and margarine are examples of saturated fat.Hydrogenation improves preser-vation, taste and odour of many oils.Soap : Soap is a sodium or potassium salt of fatty acids of long carbonchains.Saponification of Oils : Soaps can be directly obtained from oils or fats byhydrolysis in the presence of a base. This process is called saponification ofoils.C17H33COO)3C3H5+3NaOH →

3C17H33COONa + CH2OH-CH(OH)-(Soap) (Glycerol) CH2OHProcess of Soap Manufacture : Soap is manufactured from coconut, palm,cotton-seed, Soya-bean oils or animal fats.The process of soap manufacture involves three steps.

(i) Hydrolysis of fat into fatty acis.(ii) Separation of fatty acids and(iii) Neutralization of fatty acids by bases.

Soaps form insoluble compounds with Ca2+ and Mg2+ ions present in hardwater and precipitate out. This reduces the foaming and cleaning acton.Detergents also react with Ca2+ and Mg2+ ions in hard water but the productsare still soluble and do not affect the lathering and cleaning action.Detergents are salts of alkyl benzene sulphonates or fatty alcohol suphates.

CHEMISTRY AND INDUSTRY

Cement : Cement is dirty gray powder consisting of calcium silicates(2CaOSiO2, 3CaOSiO2) and calcium aluminates (3CaOAl2O3, 4CaOAl2O3) toan extent of 90%.Manufacture of Portland Cement: Cement is manufactured by two methods.Normally wet process and dry process.The heating temperature of cement is 1700-19000C.Glass : It is a transparent or translucent material.Glass is a mixture of sodium silicate, calcium silicate and sand.Raw materials of glass are soda-ash, limestone and sand.Heating temperature of glass is 10000C.Annealing : It is the process of slow cooling of the liquid glass.Colour is imparted to the glass by metal oxides/salts.Coloured Glass : When some metal oxides or metal salts are added to theglass before annealing, they impart colour to the glass.Some glasses, their properties and uses :

(i) Soda glass or soft glass : Easily fusible, used for window glass and bottles.(ii) Pyrex Glass : Used for laboratory glassware.(iii) Quartz Glass : Electrical bulbs and optical instruments.(iv) Flint-glass : Optics(v) Hard glass ; Fuses with difficulty, resistant to water and acids, used for hard

glass apparatus.(vi) Borosilicate glass : Low expansion, resistant to shock and chemicals, used

for baking dishes, laboratory glassware and pipelines.Metal oxides / Metal salts and the colourMetal oxide Colour of/metal salt the glassCr2O3 greenMnO2 purpleAuCl3 rubyCuSO4 blueCu2O redGlass-blowing : Glass-blowing is a technique by which glass articles areshaped by melting glass and blowing air into it till desired shape is obtained.The glass article is heated on a oxy-acetylene flame till red hot and air isblown by mouth or by a machine.Ceramics : Ceramics are articles made from clay and related raw materials.

Uses of Ceramics :(i) The construction of buildings as bricks and tiles.(ii) The metal industries as refractory materials.(iii) The chemical industry as stoneware and porcelain(iv) Drainage of sewage as stoneware(v) Sanitation as earthenware and vitreous china(vi) Electrical industry as insulators and porcelain.

The chief raw materials required for manufacture of ceramics are (i) clay (ii)felspar and (iii) sand.Pottery : The term pottery includes ware such as earthenware, wall tiles,electrical insulators made of porcelain and sanitaryware, glazed wall tilesetc.Pottery or Terra-cotta are products of porous nature such as pots, jugs etc.Simple pottery : This includes pottery ware made from common clays. Thearticles after drying are hearted to 11000C only and are not very strong.Earthenware : These articles are made from red clays, gray clays etc. Harderthan simple pottery because these are subjected to high temperatues ofabout 1450-18000C.Earthenware are glazed articles such as porcelain wall tiles, crucibles anddishes.Plastics : Plastics may be defined as polymeric organic material (resin)together with small amounts of other materials like fillers, plasticizers,lubricants etc.Plastics are solids in their finished state.Resin : The polymeric organic substance is commonly known as resin.Resins are classified into natural and synthetic resins.Synthetic resins are further classified into two types based on the process ofpolymerization. They are (i) resins of addition polymerization and (ii) resinsof condensation polymerization.

Uses of Plastics :(i) Polyethylene : Milk cartons, carry bags, raincoats, toys, electrical insulators,

containers.(ii) Polystyrene : Insulation, combs, ceiling tiles, packing, TV, refrigerator lining.(iii) Poly vinyl chloride : Pipes, hand bags, gramphone records, electrical

insulation, floor coverings.(iv) Polyesters : Films, recording tapes, packing and fibres for textiles.(v) Nylon 6.6 : Making bristles and brushes, carpets and fabrics, elastic hosiery.

Adhesives : Adhesives are substances capable of holding materials togetherby surface attachement Adhesives are of two types, viz., (i) natural adhesivesand (ii) synthetic adhesives.Gum-Arabica, shellac, animal glue made from bones or hides of animalsand fish are a few examples of natural adhesives.

Synthetic adhesives are resins such as epoxy resins, silicones, phenol-urea-formaldehyde resin, poly vinyls, poly styrenes and poly amides.Fibres : Fibres are materials used to weave cloth in textile industry. Fibreseither natural or artificial are derived from polymer compounds.Cellulose (poly glucose) is the main constituent in the natural fibres.Man-made fibres are delivered from synthetic polymers.The requirements for a polymer to be used as fibre are as follows:

(i) Polymer should have high tensile strength so that strong fibres may beobtained.

(ii) It should withstand pressure and temperature of washing and ironing.(iii) It should resist hydrolysis due to bases during washing.(iv) It should be capable of being dyed.(v) It should resist the effect of dry cleaning solvents.(vi) It should be resistant to sunlight, heat and air oxidation.

Methods of spinning :(i) Melt Spinning (ii) Dry Spinning.Cosmetics : Any substance, preparation or treatment applied to the personto cleanse, beautify, alter the appearnace or to promote the attractiveness ofthe person is called cosmetic.Cold Creams : Cold creams are used as cosmetics for skin. They protect theskin from hot sun, effect of cold breeze and dust.Nail Polish : Nail polish is a cosmetic applied on nails for attraction. Itconsists of a polymeric resin, a plasticizer, colouring pigments and perfumedissolved in a mixture of low boiling solvents.Face-powder: Face-powder is the largest selling single item among thecosmetics. It is applied to the face to remove oil and sweat and impartsmooth finish to the skin. Face-powder has five characteristics.(i) Opacity (ii) Slip (iii) Adherence (iv) Absorbency (v) Fineness.Dyes are useful for colouring textiles. Chromophore and auxochrome aretwo groups that must be present in a dye.Dyes are classified into acidic, basic, direct, modrant, vat etc., dependingupon the method of application of dye to the fibre.Drugs : Drugs are substances used in prevention, diagnosis, treatment orcure of a disease.Drugs are classified into six types based on therapeutic action. They are (i)Drugs working on central nervous system (ii) Drugs working on cardiovascularsystem, (iii) drugs working on foreign organisms. (iv) Chemo therapeuticdrugs (v) vitamins and (vi) harmones.Pharmaceuticals are modified forms of drugs such as tablets, capsules,lotions, syrups, tonics and injections.Petroleum is found deep in the earth’s crust and is pumped out by air liftpump.Refining of petroleum gives many useful organic compounds viz., cooking

gas, petroleum ether, naphtha, kerosene, petrol, diesel, lubricating oil, roadtar etc.Petroleum products are converted into organic chemicals calledpetrochemicals. Petrochemicals in turn are converted into many usefulproducts.Cooking gas is a mixture of butane, propene and propane compressed toliquid form called “liquified petroleum gas”. (LPG).Plants derive their nutrients from soil, water and air.Fertilizers provide N, P and K to the plants.Urea, ammonium phosphates, super phosphates are a few examples offertilizers.

CLASS - IXBEHAVIOUR OF GASES

There are three states of matter :(i) Solid : Solid has a definite shape and occupies only a definite volume.(ii) Liquid : Liquid does not have a definite shape. It takes the shape of the

container.(iii) Gas : A gas does not have a definite shape like a solid. Gases also take the

shape of a container in which they are stored.Properties of Gas :

(i) A gas is composed of very small particles which are called molecules. Thedistance between gas molecules is greater than that in the case of solids andliquids.

(ii) The force of attraction between the molecules of a gas is negligible.(iii) Molecules of a gas move in different directions.(iv) The gas molecules move in straight lines.(v) The gas molecules undergo random collisions.(vi) Gases are light and possess very little weight.(vii) Gas exerts pressure and occupies space.(viii) The volume of a given mass of gas can be easily compressed.(ix) Gas exhibits diffusion property.

Boyle’s law : The volume (V) of a given mass of gas is inversely proportionalto its pressure (P) at any given temperature (T).

P1V α or PV = Constant.

Charle’s Law : At constant pressure, volume of a given mass of gas increaseswith an increase in temperature or decreases with a decrease in temperature

by a value 2731

of its original volume at 00C for every one centigrade degree in

temperature.

TVorTV α = Constant.

or t273VVV 0

0t

+=

where t = temperature in centigrade degrees, V0 and Vt are the volumes at 00Cand t0C respectively.Graham’s Law of diffusion : Under similar conditions of temperature andpressure the rates of diffusion of gases (distance covered in one second) areinversely proportional to the square roots of their densities or molecular weights.Lighter gases diffuse faster than heavier gases. This property is useful indetecting marsh gas in coal mines.

ATOMIC STRUCTURE

Atom :(i) Atoms are the basic building blocks of matter.(ii) Atoms are the smallest units of an element.(iii) Atoms combine to form molecules.(iv) According to modern theories, atoms contain positively charged nucleus

and negatively charged electrons.Dalton’s postulates of Atomic Theory:

(i) Matter is composed of the smallest particles called as “atoms” which cannot bedivided further.

(ii) Atoms of the same element are alike and behave in the same way in allrespects.

(iii) Atoms of different elements are different from each other in all respects.(iv) Atoms of either same or different elements combine with each other and

give new particles. These are named as “compound atoms”.(v)Atom is the only particle which participates in a chemical reaction.

Cathode Rays :J.J. Thomson discovered negatively charged cathode rays in discharge tubeexperiment.Properties or Cathode Rays :

(i). Cathode rays travel in straight lines from cathode to anode.(ii) Cathode ray beam deviated its path under the influence of magnetic or

electrical fields.(iii) Cathode rays can cause a shadow when an object is placed in their path.(iv). Cathode rays create mechanical motion.

Electron :(i) G.J. Stoney named the cathode ray particle as electron.(ii) Charge of an electron is 1.06 x 10-19 coulombs.(iii) Mass of an electron is 9.10 x 10-28 gm.

Canal / Anode rays : Goldstein discovered anode rays.Properties of anode rays :

(i) Anode rays travel in straight lines.(ii) Anode rays deviated their path towards a negatively charged electrode when

an electric field was applied.(iii) When magnetic field was applied anode rays were deflected towards south

pole.(iv) The e/m ratio of anode rays particles was same when different gases were

used in discharge tube.

Neutron : James Chadwick invented neutron. It does not possess charge butits mass is almost equal to mass of a proton.Atomic Model :An atomic model depicts a systematic arrangement of electrons, protons andneutrons in an atom.It was proposed that an atom contains equal number of electrons and protons.Atomic number (Z) = No. of protons = No. of electrons.Atomic Mass (or) Mass Number : Atomic mass or mass number is the sum ofthe number of protons and neutrons.J.J.Thomson’s Atomic Model : J.J. Thomson’s atomic model states thatelectrons are embedded in the positively charged atomic mass like seedsembedded in the fibrous mass of a watermelon fruit.Alpha ( ∝ ) Particle : When two electrons are removed from helium atom, theresultant entity is defined as an alpha ( ∝ ) particle.Rutherford’s Atomic Model : Rutherford’s atomic model can be compared tothe solar system. Electrons revolve round the positively charged atomic nucleusin certain orbits like planets revolve round the sun in certain orbits in solarsystem. Therefore, Rutherford’s atomic model is some times called as planetaryatomic model.Atomic Number : Atomic number (Z) is defined as the number of protons orthe number of electrons present in an atom.Particles which are present in an atom are known as subatomic particles. Proton,electron and neutron are known as the main subatomic particles. However,there are several hundreds of subatomic particles.Nucleons : Particles which are present in a nucleus are known as nucleons.Neutron and proton are the important nucleons.

CHEMICAL BONDING

Chemical Bond : A Chemical Bond is an attractive force between two atoms ina molecule.Valence Electron : Electrons present in the outermost orbit of an atom areknown as valence electrons.Atoms with eight electrons in their outermost orbit are stable. Except helium,all the rare gases have eight electrons in their outermost orbits.Every atom has a tendency to acquire the electronic configuration of the nearestnoble gas and becomes more stable.Molecules have lower energy than that of combined atoms. molecules are morestable than atoms.Ions : Ions are charged paricles. They are formed when the transfer of electronsoccurs from the outer most orbit of one atom to the outermost orbit of another.The atom which loses electron acquires positive charge and the atoms gainingelectrons acquire negative charge.Ionic bond : The ions are bonded together by their electrical charges. Such abond is called ionic bond.During the formation of an ionic bond, transfer of electron(s) occurs from oneatom to the other.One atom loses electron(s) from its outermost orbit, forms a positive ion (cation)and thereby attains the electronic configuration of nearest noble gas.Other atom gains electron (s), forms a negative ion (anion) and attains theelectronic configuration of nearest noble gas.Ionic bond is formed due to the attraction between the oppositely charged ions.Oxidation : Loss of Electrons is called oxidation.Reduction : Gain in Electrons is Reduction.Properties of Ionic substances :

(i) Ionic substances are crystalline solids.(ii) Ionic compounds exhibit high melting points.(iii) Ionic compounds are soluble in polar solvents and insoluble in non polar

solvents.(iv) Ionic compounds conduct electricity both in molten state and also in aqueous

solutions.Covalent Bond : Atoms acquire stability by sharing of electrons betweenthemselves. The two atoms are held by the attractive forces between the pairof electrons and the two nuclei. Such a force holding the atoms is called covalentbond. .Covalent Compounds : The compounds containing molecules which are formedby sharing of electrons are known as covalent compounds.

Properties of Covalent Compounds :(i). Melting and boiling points of covalent compounds are lower than ionic

compounds.(ii) Covalent compounds are soluble in non polar solvents and insoluble in

polar solvents. Covalent compounds are poor conductors of heat and electricity.(iii) Covalent bond is not only rigid but is directional and have definite geometry

about them.Polar Molecules : Molecules having two oppositely charged poles are calledpolar molecules.In the non-polar molecules the two atoms attract the pair of electrons equally.The molecule thus formed is non polar.Polar Covalent : When two unlike atoms combine, one of them may attract thebonding electrons more to it self than the other, resulting in unequal distributionof the electron pair between them. Such a bond is called polar covalent bond.Vander Waals forces : All molecules exert weak attraction upon one another.These attractions are called Vander Waals forces.Vander Waals forces are purely electrostatic forces operating between moleculesat a short distance.A dipolar molecule attracting another dipolar molecule is called dipole-dipoleattraction.

ENERGETICS

Bond Dissociation Energy : Energy is required to break a bond. Such energyis called Bond Dissociation Energy.Bond energy : When a new bond is formed, certain amount of energy is released.Such energy is called bond energy.Endothermic Reaction : A chemical reaction which takes place with theabsorption of heat is known as an endothermic reaction.Exothermic Reaction : A chemical reaction which is accompanied by therelease of heat energy is called as an exothermic reaction.Photosynthesis : Synthesis of starch by plants from carbondioxide and waterin the presence of sunlight is called photosynthesis.Energy is stored in the molecules in different forms, namely, binding energy,rotational energy, kinetic energy and vibrational energy.Energy stored in the molecule is called internal or intrinsic energy which dependson its chemical composition (structure) and physical state.In endothermic reactions heat is absorbed by the reactants.An exothermic reaction is associated with the release of energy.

CHEMICAL CALCULATIONS

Symbol : A Symbol represents a shorthand notation of an element.A coefficient (a number) preceeding the symbol indicates number of atoms.A subscript of the symbol also represents number of atoms.Formula : Formula is defined as a symbolic representation of actual numberof atoms present in a molecule of a substance.Number preceeding the fomula indicate the number of molecules of a substance.Chemical Equation : Chemical equation is a shorthand representation of achemical change or reaction in terms of symbols and formulae.Reactants : The substances which take part in a chemical reaction are knownare reactants.Products : Substances formed due to chemical change are known as products.Reactants are written on the left-hand side of the equation, connected by aplus (+) sign.Products are written on the right-hand side of the equation, connected by aplus (+) sign.Reactants and products are seperated by an arrow (->).Balanced Equation : A balanced equation can be defined as a chemical equationin which number of atoms of each element is same on both the sides of achemical reaction.Electrochemical Reactions : The reactions which take place only with theabsorption of electrical energy are called electrochemical reactions.Avogadro’s Hypothesis : Under the same conditions of temperature andpressure equal volumes of all gases contain equal number of molecules. Gram Molecular Weight : “Gram molecular weight” can be defined as therelative molecular mass of a substance expressed in grams with reference tothe atomic weight of hydrogen. Some times it is called as “gram molecule” ofthat element. Molar volume or Gram molecular volume and Avogadro number : “Grammolecular volume or molar volume can be defined as the volume occupied byone gram molecular weight (gram molecule) of a gas at STP”. It wasexperimentally shown that “one gram molecular weight of a gas at STP occupies22.4 litres”. Mole Concept : One mole or 1 gram atomic weight of a substance containsAvogadro number (6.023 x 1023) of atoms.One mole or 1 gram molecular weight of compound contains Avogadro number(6.023x1023) of molecules.In Weight-Volume relationships, calculations are made on the basis that atSTP, one mole of gas occupies a volume of 22.4 litres.

RATES OF REACTIONS

Fast Reactions : Reactions, which take place (instataneously) within a secondare known as fast reactions.Moderate Reactions : Reactions taking place in a few minutes to few hoursare defined as moderate reactions.Slow Reactions : Reactions taking place in several hours and above are definedas slow reactions.Rate of the Reaction : Rate of the reaction can be defined as change in theconcentration of reactant or product in one second.Rate of the reaction depends on the nature of reactants used.Rate of the reaction depends on the concentration of reaction. If concentrationof a reactant is increased rate is generally increased.Catalyst : A catalyst can be defined as a substance which alters the rate of areaction without undergoing any chemical change.An increase in temperature increases the reaction rate. For every 100 rise intemperature, rate of the reaction is generally doubled or tripled.Reversible Reaction : In a reversible reaction, products are reconverted to thereactants.Irreversible Reaction : In an Irreversible reaction, products cannot be convertedinto the reactants.Equilibrium State : When the rate of forward reaction is equal to the rate ofbackward reaction, the system is said to be in a state of equilibrium.A reversible reaction is said to be in a state of equilibrium when the rate offorward reaction is equal to the rate of backward reaction.Concentration, Pressure, Temperature and Catalyst often influence theequilibrium state.An increase in the concentration of reactants increases the rate of forwardreaction and equilibrium shifts to right side.An increase in the concenrtration of products increases the rate of backwardreaction and equilibrium shifts to left side.

METALLURGY

Minerals : Compounds of metals which occur in nature with other materialssuch as sand, rock and clay as impurities and which are obtained by miningare called minerals.Ores : The minerals from which metals can be profitably extracted are calledores.India has rich mineral resources like Iron, Manganese, Copper, Gold,Aluminium, Tin, Chromium, Limestone, Monazite, Lead and Zinc etc.Metallurgy : The method of extraction of the metals from their ores and thepreparation of alloys is called metallurgy.Dressing or Concentraton of the ore: The removal of unwanted impurities bymechanical and other physical methods is known as ore dressing orconcentration.Extraction of the metals from its ores involves one or more of the followingprocesses. 1. Calcination, 2. Roasting and 3. Smelting.Calcination : Calcination is a process in which ore is subjected to the actionof heat in the absence of air.Roasting : Roasting is heating the ore in the presence of air.Smelting : Smelting reduces the ore into molten metal by heating it with fluxat high temperature.Flux : Flux is material which combines with the impurities (gangue) and convertthem to a fusible material called slag.Iron in elemental state occurs in meteorities. Iron is an important constituentof haemoglobin of blood. Iron is also present in plant and animal tissues.Metallurgy of Iron : The metallurgy of Iron involves the manufacture of castiron.Following Steps are important in the manufacturing of cast Iron :

(a) Concentration of the Ore(b) Calcination(c)Smelting

Pig Iron : The molten metal with drawn from the furnace is called Pig Iron.Wrought Iron : Wrought iron is comparitively pure form of iron. It containsnot more than 0.5 percent impurities of which carbon amount to about 0.2percent.The other impurities are sulphur, phosphorous, silicon and manganese.Steel : The carbon content of steel is 0.1 to 1.5 precent and is intermediatebetween that of cast iron and wrought iron. The hardnes of steel increaseswith the increase in carbon content.Uses of Steel : Varioussteels are used for the purpose like watch springs,safety razor blades, manufacture of rails, locomotives, war implements, surgicalinstruments, cutlery etc.

Alloy Steels : Steel is an alloy is iron and carbon. About 92% of alloy steels arecarbon steals.Advantages of Open Hearth Process:

(i) A regenerative system of heat economy is employed to save the fuel.(ii) The composition of the product and also the temperature can be controlled.(iii) The composition of steel can be controlled easily.(iv) The steel obtained is of better quality.

Following methods are in use to protect the metals :(i) In the galvanizing process, steel plate is protected by a coating of zinc.(ii) Electroplating process involves a cathode and anode and deposition or

plating takes place on the cathode.(iii) Alloying protects the metals from corrosion and gives them special properties.

Mode of Occurence of some Metal

Chemical nature Metalsof mineralsNative Cu, Ag, Au, Hg, As, Sb, BiOxide Fe, Al, Mn, Sn, Ti, Zr, CrSulphides Zn, Cd, Hg, Cu, Pb, Fe, CO, Ni, MO, As, Sb, Bi, Ag.Carbonates Mg, Ca, Sr, Ba, Fe, Pb, Zn, Cu.Halide Na, K, Rb, Cs, Mg, Ca, AgSulphate Ca, Sr, Ba, Mg, PbSilicate Li, Na, K, Mg, Ca, Be, Al, Fe, Zn, Ni.

Some Common OresChemical Formula Metal Kind

of OreHaematite Fe2O3 Iron OxideIron pyrite FeS Iron SulphideCopperpyrite CuFeS2 Copper SulphideCopperglance CuS Copper SulphideBauxite Al2O3 Aluminium OxideGalena PbS Lead SulphideLitharge PbO Lead OxideMagnesite MgCO3 Magnesium CarbonatePyrolusite MnO2 Manganese OxidePitchblende U3O8 Uranium OxideMonazite ThO2 Thorium Oxide

Rocksalt (halite) NaCl Sodium ChlorideCerussite PbCO3 Lead Carbonate

Some metals like nickel, manganese, chromium, molybdenum, vanadium,tungsten with certain percentage form alloys with steel.

CLASS - VIII

ACTION OF HEAT ON SUBSTANCES

When substances are heated, they undergo changes such as change in colour,state, composition etc., These changes may be physical or chemical.Sublimation of sold iodine :

I2 I2

(Solid) (vapours)

Action of heat on Ammonium chloride (NH4Cl) :

NH4Cl NH4Cl(Solid) (white denser fumes)

Action of heat on Zinc oxide :

ZnO ZnO(White) (yellow)

Action of heat of lead oxide :

PbO PbOLead Oxide Lead Oxide(yellow) (brown)

Physical Change :The physical changes produced in the substances by heating can be reversedon reversing the conditions.Characteristics of physical changes:

(i) Change takes place only in the physical properties of the substancesuch as state, co lour, volume etc.,

(ii) The composition of the substance remains the same throughout thechange

(iii) The weight of the substance undergoing a physical change remain thesame.

(iv) Physical change may also be brought about by applying other forms ofenergy such as light, electricity etc.,

(v) The change is purely temporary. By reversing the conditions the changecan be revesed.

Characteristics of a chemical change:(i) Change takes place in the chemical composition of the substance.(ii) The fundamental properties of the products are different from those of

the original substances (reactants).(iii) Energy change occurs during chemical change in the form of heat, light

electricity and sound.(iv) Chemical change is permanent and cannot be easily reversed . New

substances are formed as a result of change.Sublimation of iodine, conversion of liquid water into water vapour,magnetisation of iron piece are some examples in which heat produces nochange in chemical composition.

SYMBOLS, FORMULAE AND EQUATIONS

The symbols are some of the elements along with their atomic weights aregiven below :

S.No. Element Symbol AtomicWeight

1 Hydrogen H 1.0082. Helium He 4.00263. Lithium Li 6.944. Beryllium Be 9.01225. Boron B 10.8116. Carbon C 12.0117. Nitrogen N 14.00678. Oxygen O 15.9999. Flourine F 18.99810. Neon Ne 20.18311. Sodium Na 22.98912. Magnesium Mg 24.31213. Aluminium Al 26.9814. Silicon Si 28.08615. Phosphorus P 30.97416. Sulphur S 32.06417. Chlorine Cl 35.45318. Argon Ar 39.94819. Potassium K 39.10220. Calcium Ca 40.0821. Scandium Sc 44.95622. Titanium Ti 47.9023. Vanadium V 50.94224 Chromium Cr 51.99625. Manganese Mn 54.93826. Ferrum Fe 55.84727. Cobalt Co 58.93328. Nickel Ni 58.7129. Copper Cu 63.5430 Zinc Zn 65.37

The symbol for an element represents the element either as pure state or incombined state.

An atom is the smallest particle of an element .A molecule is the smallest unit of matter capable of independent existence.The representation of a molecule of an element or a compound in terms ofsymbols and figures is defined as chemical formula.

Examples : H2, H2O, SO2, NH3, O3, H2 SO4

Element/Compound FormulaHydrogen H2

Nitrogen N2

Oxygen O2

Ozone O3

Water H2OSulphur dioxide SO2

Sulphuric acid H2SO4

Nitric acid HNO3

Hydrochloric acid HClSodium hydroxide(caustic soda) NaOHCalcium hydroxide Ca(OH)2Sodium chloride(common salt) NaClSodium carbonate(washing soda) Na2CO3

Sodium bicarbonate(cooking soda) NaHCO3

Ammonium chloride NH4ClHydrogen peroxide H2O2

Silver nitrate AgNO3

Monovalent radicals :S.No. Name of Formula Charge

the radical1. Hydrogen H+ 12. Sodium Na+ 13. Potassium K+ 14. Ammonium NH4

+ 15. Chloride Cl- 16. Hydroxide OH- 17. Chlorate ClO3

- 18. Bicarbonate HCO3

- 19. Bisulphate HSO4

- 110. Permanganate MnO4

- 1

The formula of calcium chloride is CaCl2The formula of sodium chloride is Nacl.

The formula of sodium carbonate is 32CoNa

The Formula of aluminium chloride 3AlCl .

The least possible ratio of atoms in a molecule enables writing down theemperical formula . on the other hand molecular formula represents the ratioof atoms actually present in the molecule.Chemical Equation : Chemical reactions can also be represented in short byusing the formula of substances involved in a reaction. This is known aschemical equation.

dioxideCarbonOxygenCarbon →+

product2

tstanreac2 COOC ↑→↑+

The substances which react are called “reactants”. Substances which areformed are called “Products”.Radical or ion is formed by loss or gain of electron(s)by atoms. They carrycharges.Radicals or ions can have valency 1,2,3 etc.,Formulae of molecules should satisfy the valencies of all the elements of whichthey are made.Chemical equation gives the number of atoms or molecules of the reactantsand the productsBased on the balanced chemical equation the weights in grams of the reactantsand the products can be calculated.

TYPES OF CHEMICAL CHANGES

There are four types of Chemical Changes:(i) Combination(ii) Decomposition(iii) Displacement and(iv) Double Decomposition.

Combination : Two or more substances combining to give a single substanceis called Combination

Eg : ↑→↑+ 22 SOOS

Decomposition : A single substance splitting into two or more substances iscalled decomposition.

Eg : ↑+→ 23 COCaOCaCO

Displacement : If one element or radial replaces another element or radical ina substance is called displacement reaction.

Eg : CuZnSOCuSOZn 44 +→+

Double Decomposition : Mutual exchange of elements or radicals by twosubstances is known as double decomposition.

Eg: NaCl2BaSOSONaBaCl 4422 +↓→+

LAWS OF CHEMICAL COMBINATION

The Laws of Chemical combination are:(i) Law of conservation of mass(ii) Law of definite proportions(iii) Law of multiple proportions.

Law of conservation of Mass : During a chemical change matter is neithercreated nor destroyed. But it undergoes physical and chemical changes. Thisis known as the law of conservation of mass.Law of Definite Proportions: When two or more elements combine to form acompound they combine in a fixed ratio of their weights. The ratio is independentof the method of formation of the compound. This law is known as law ofdefinite proportions.Law of Multiple Proportions : The weights of one element that separatelycombines with a fixed weight of another element bear a simple integral ratio..This law is known as law of multiple proportions.

WATER AND ITS CONSTITUENTS

Water :About sixty to seventy percent of our body comprises of water. Cavendishprepared water in 1784, by igniting a mixture of two volumes of hydrogen andone volume of oxygen.The synthesis proved that water is a chemical compound of hydrogen andoxygen. It can be called as hydrogen monoxide.If the composition is expressed in terms of volumes of the elements, it givesthe volumetric composition. If it is expressed in weight, it gives the gravimetriccompositionElectrolysis : The process of decomposing water into its elements by passingelectricity is called electrolysis of waterWater is a natural compound of hydrogen and oxygen. It is the most widespreadsubstance on earthWater is present in all food stuffs and living beings.Water is a universal solvent i.e. it has great ability to dissolve many substances.Natural water contains suspended and dissolved impurities. Distilled water isthe purest form of water.Some gases get dissolved in water. Some water is hard and some water is soft.Hardness is due to presence of salts such as CaCl2, MgCl2, CaSo4, MgSo4,Ca(HCO3)2, Mg (HCO3)2, etc.,. it can be removed by boiling water or by addinglime alum etc.Water for drinking purposes in big cities and towns comes from rivers or lakes.It is purified by pumping into (a) Sedimentation tank, (b)Filter tank and (c)Chlorination tank, before being supplied for drinking purposes.Hydrogen :Hydrogen is the lightest of all gases.Hydrogen is abundantly found in the atmosphere of the sun and the otherstars.Hydrogen is the lightest gaseous element known.Air is 14.5 times as heavy as Hydrogen.Hydrogen is a colourless gas, almost insoluble in water.Hydrogen burns in air with pop sound and forms water.Hydrogen is prepared in the laboratory from zinc granules and dilute sulphuricacid.Zinc magnesium , aluminum or iron displaces hydrogen from diluted H 2 SO4and HNO3. But copper, mercury or platinum does not displace hydrogen fromacids.Hydrogen converts metal oxides into metals.Hydrogen reacts with nitrogen chlorine, and sulphur to give ammonia, hydrogen

cloride and hydrogen sulphide respectively.Hydrogen is used to fill weather balloons.Hydrogen is used to convert vegetable oils like groundnut oil, cotton seed oil,coconut oil into solid fats. The process is called hydrogenation of oils.A mixture of hydrogen and oxygen burns and gives a very hot flame which iscalled oxyhydrogen flame.Laboratory preparation of Hydrogen:Hydrogen can be prepared from compounds like water. And by the action ofhydrochloric acid or sulphuric acid on zinc.The Chemical reaction taking place between Zinc and Hydrochloric acid canbe represented as follows.

↑+→+ 22 HZnClHCl2Zn

OXYGEN :Oxygen is the most abundant element on earth.Oxygen is a colourless, odourless gas and slightly soluble in water.Oxygen is a good supporter of combustion. When substances burn in oxygen,they form oxides .Oxides are of three types: (a) basic oxides, (b)acidic oxides and (c) neutraloxides. Metals usually form basic oxides which form bases with water. Non-metals form acidic oxides which form acids with water.Acidic oxides turn blue litmus to red, and basic oxides turn red litmus to blue.Neutral oxides do not change the colour of litmus paper.An indicator(litmus paper) is a substance which by a suitable colour changeindicates whether a given solution is acdic or basic.Laboratory Preparation Oxyzen :

↑+→ 23 O3KCl2KClO2 ↑+→ 223 OKNO2KNO2

↑+→ 223 ONaNONaNO2

Preparation of oxygen by heating KMnO4

↑++→ 22424 OMnOMnOKKMnO2

Preparation of oxygen from hydrogen peroxide (H2O2)

222

22 OOH2MnOOH2 + →

Substances such as H2O2, HgO, KMnO4, KNO3, KCIO3, NaNO3 Liberate Oxygenon heating.Catalyst : A catalyst alters the rate of a chemical reaction without itselfundergoing any change in weight and chemical composition.Combustion : Burning substances in oxygen is called combustion.Oxidation : Oxidation is process in which oxygen is added or hydrogen isremoved from its compounds.Reduction : Reduction is a process in which hydrogen is added, or oxygen isremoved from any of its compounds.Air Pollution : The contamination of the air by dust and toxic vapours is calledair pollution.

SULPHUR AND ITS COMPOUNDS

There are two processes for the extraction of sulphur, (1)Sicilian process and(2)Frasch Process.Sulphur occurs in nature in elemental form and also in combined state e.g.sulphides and sulphates.Sulphur is extracted through the sicilian process from the deposits occurringon the earth’s crest containing 30% sulphur and through Frasch Process wherefree sulphur occurs underground.Allotropy : The existence of an element in two or more different physical formsis called allotropy. The allotropic forms possess identical chemical propertiesbut differ in physical properties.The three important allotropic forms of sulphur are rhombic sulphur, monoclinicsulphur and plastic sulphur.Sulphur is yellow solid insoluble in water but soluble in carbon disulphide.Metals such as mercury , zinc and copper react with sulphur and form metallicsulphides.Rhombic and Monoclinic sulphur are composed of S8 molecules.Sulphur is used:

(i) in the manufacture of sulphuric acid(ii) in the manufacture of fire works gun powder and matches(iii) in the manufacture of fungicides(iv) in vulcanisation of rubber

Sulphur burns in air and forms sulphur dioxide, which is a poisonous gascapable of causing inflammation in lungs.Sulphur dioxide :Sulphur forms two oxides, sulphur dioxide (SO2) and sulphur trioxide (SO3).Laboratory preparation of Sulphur dioxide :Sulphur dioxide is prepared in the laboratory by heating concentrated sulphuricacid with copper turnings.

↑++→+ 22442 SOOH2CuSOSOH2Cu

Sulphur dioxide is neither combustible nor a supporter of combustion.Acidic nature: Sulphur dioxide combines with water to form sulphurous acid

3222 SOHOHSO →+↑

Sulphur dioxide as reducing agent: Sulphur dioxide reacts with moistureand liberates nasent hydrogen.

hydrogennascent4222 H2SOHOH2SO ↑+→+↑

In the presence of moisture, sulphur dioxide gives nascent hydrogen. Thisnascent hydrogen combines with vegetable and animal colouring matter andrenders it colourless

hydrogennascent4222 H2SOHOH2SO ↑+→+↑

Sulphur dioxide is heavier than air.Manufacture of Sulphuric Acid :Sulphuric acid called as “the king of the chemicals”. It is prepared by (a)Contact Process and (b) Lead chamber process.Sulphur trioxide should not be dissolved in water as this is an explosive reaction.Oleum is also called disulphuric acid. Oleum on treating with water givessulphuric acid.Physical properties :

(i) Sulphuric acid is a colourless odourless oily liquid.(ii) On boiling, the pure acid decomposes giving off water vapour and dense

white fumes of sulphur trioxide.

↑+→ 32heat

42 SOOHSOH

(iii Sulphuric acid is soluble in water in all proportions.Chemical properties :

(i) Sulphuric acid reacts with sodium hydroxide and basic oxides giving rise tocorresponding salts.

OH2SONaSOHNaOH2 24242 +→+

(ii) Metals like iron, zinc and magnesium react with dilute sulphuric acid andliberate hydrogen.

↑+→+ 2442 HZnSOSOHZn

(iii) Sulphuric acid gives (i) Hydrogen chloride from chlorides (ii) Nitric acidfrom nitrates, on heating (iii)Hydrogen sulphide from sulphides. Sulphur dioxideor sulphurous acid from sulphites.

↑+→+ HClNaHSOSOHNaCl 442

34423 HNOKHSOSOHKNO +→+

↑++→+ 22424232 COOHSONaSOHCONa

Sulphuric acid as oxidising agent :Sulphuric acid decomposes and gives oxygen.

↑+↑+→ )O(SOOHSOH 2242

Concentrated sulphuric acid has great affinity for water. It removes waterfrom many substances.Uses : Sulphuric acid is used in the manufacture of fertilizers, pigments, storagebatteries, detergents and explosives.Hydrogen Sulphide :Hydrogen sulphide is not a supporter of combustion but it is combustible.Hydrogen sulphide is colourless gas with the smell of rotten eggs. It is producedwhen sulphur is heated with hydrogen.Hydrogen sulphide is heavier than air.Filter paper dipped in lead acetate turns black when it is exposed to hydrogensulphide due to formation of black lead sulphide.The Kipp’s apparatus is used for intermittent supply of hydrogen sulphide.

NITROGEN AND ITS COMPOUNDS

NITROGEN :Air consists of 75% by weight and 80% by volume.It is available in nature in the form of compound like the nitrates and urea.Nitogen is an essential constituent of all animal and plant tissues.Nitrogen is manufactured by fractional distillation of liquid air.Ammonium Nitrate is an explosive and cannot be heated directly to get nitrogengas.Properties of Nitrogen :

(i) It is a colourless, odourless and tasteless gas.(ii) It is slightly lighter than air and is slightly soluble in water.(iii) It is not poisonous.(iv) It is an unreactive gas and solidifies to colourless solid.

It is neither supporter of combustion nor combustible.It is chemically an inert gas. It combines with some elements at highertemperatures to give their compounds. It is used in the manufacture of ammonia,fertilizers and explosives.Liquid nitrogen is used as cooling agent for certain reactions carried at verylow temperature.Ammonia :Ammonia can be obtained in the laboratory by heating ammonium chloridewith quick lime or sodium hydroxide.Ammonia is a colourless pungent smelling gas. It is lighter than air.Ammonia is neither a supporter of combustion nor combustible.Ammonia is a base. It reacts with acids to form ammonium salts.Ammonia is a good reducing agent. It reduces metal oxides to metalsIt also reduces chlorine to hydrogen chloride.Ammonia Salts:When ammonium hydroxide is neutralized with acids the correspondingammonium salts are obtainedAmmonia chloride is used in soldering industry and in dry cells as an electrolyte.Ammonium nitrate is used in the manufacture of explosives and as a fertilizerin mixed fertilizers with calcium salts.Ammonium sulphate is used as a fertilizer.Ammonium phosphate and Calcium ammonium nitrate are also used asfertilizers.

Nitric Acid

Nitric acid is obtained by heating a mixture of potassium nitrate andconcentrated Sulphuric acid in the laboratoryNitric acid is a strong acid. It reacts with bases and basic oxides to give nitrates.Nitric acid reacts with many metals. But the products of the reaction dependupon the nature of the metal concentration of the acid and temperature.Nitric acid is a powerful oxidizing agents:

(i) It oxidizes non metals carbon , Sulphur and phosphorus to their oxides. Theyform acids when they react with water.

(ii) It oxidizes hydrogen sulphide to sulphur.Fixation of nitrogen and nitrogen cycle :The conversion of atmospheric nitrogen into nitrogenous compoundsFixation of atmospheric nitrogen takes place in nature during lightning, bybacterial conversion and by artificial production of ammonia and nitrates.Denitrifying bacteria converts nitrogenous compounds into nitrogen which isreturned to the atmosphere. This keeps the percentage of atmospheric nitrogenconstant

PHOSPHORUS AND ITS COMPOUNDS

Phosphorus is a very reactive and does not occur free in natureIt occurs in combined state as Phosphates.It is present in egggyolk, bone marrow and brain of animal.Bones contain 50% of calcium phosphate.Phosphorus is obtained by heating a mixture of powdered phosphorous orewith sand and coke in an electic furnace.

OH2CO10PC10HPO4 243 ++→+

Elemental Phosphorus occurs as P4

P4 is colourless waxy solid but turns yellow on standing.It is melt only under water as it is very reactive.It causes jawbones decay to the labours woking with it.Phosphorescence : If Phosphorus is exposed to air in dark, it glows because ofslow combustion. This is known as phosphorescence.Phosphorus combines with calcium to give calcium phosphide.

23PCaCa3P2 →+

It reacts with metals to give metal phosphides.It exhibits allotropy and is used in match industry.Phosphorus forms many important compounds like phosphorus pentoxide,phosphoric acid and super phosphate of lime.Phosphorus burns in Oxygen to give phosphorus pentoxide. This is a hygroscopicsubstance. It is used as a dehydrating agent.Phosphorus pentoxide dissolves in hot water to give phosphoric acid.Phosphoric acid is a tribasic acid and gives three different types of salts.Phosphoric acid is used in the manufacture of phosphates and in medicines.Superphosphate of lime is prepared by mixing phosphate rock with concentratedsulphuric acid. This is used as a fertilizer.

COMMON SALT AND ITS CONSTITUENTS

Common salt (Sodium Chloride) is one of the important substances used inour daily life.Common salt is available as rock –salt and sea-water contains 2.8 per cent ofcommon salt. 60 per cent of our requirement is met from sea-water.Sea-water is allowed to evaporate from salt meadows under sun’s heat. Thesolid separates.Salt obtained from sea-water contains impurities. They are removed by addingsodium carbonate and calcium hydroxide.Impurities from salt are removed by bubbling hydrogen chloride gas throughconcentrated solution of sodium chloride.Common salt is used to give taste to food in preserving food and in chemicalindustries.Uses : To give taste to food.For storage of meat and fish and to make pickles.To prepare freezing mixture with ice to get temperature below 0

0C.

In the manufacture of chlorine, sodium metal and hydochloric acid.Caustic soda (NaOH), washing soda (Na2 CO3 )and sodium sulphate.In soap industry for ‘salting out’.soap.Electrolysis of Brine :Water solution of sodium chloride is called brine.Electrolysis of brine gives chlorine, hydrogen and sodium hydroxide. This isbrought about by either Castner-Kellner Cell or by Nelson’s Cell.Chlorine obtained as a by-product is liquified and stored in steel cylinders.Another by-product is hydrogen and it is stored for using in Haber’s process.Chlorine :Oxidation of hydrochloric acid with manganese dioxide or potassiumpermanganate gives chlorine.Eljectrolysis of brine also gives chlorine.Chlorine is a greenish yellow gas with pungent smell.It is heavier than air and is slightly soluble in water. The solution of chlorine inwater is called chlorine water.It does not burn and does not support combustion.It oxidizes substances like hydrogen sulphide, ammonia and turpentine due toits greater affinity for hydrogen.It reacts with phosphorus (a non metal) to give phosphorus to pentachoride.It bleaches organic substances by oxidationIt reacts with slaked lime to give bleaching powder.Chlorine is used (a) for sterilizing drinking water (b)to produce bleaching powder.

Hydrogen Chloride :Hydrogen chloride is a gas. The gas when dissolved in water is calledhydrochloric acid.Sodium Chloride on treating with concentrated sulphuric acid gives hydrogenchloride.Hydrogen chloride is a colourless gas with suffocating odour.It fumes in moist air.Hydrogen chloride reacts with ammonia to give ammonium chloride.It is highly soluble in water and the solution is acidic in nature. It is calledhydrochloric acid.It is used in the preparation of chlorine and as a common reagent in thelaboratory.

CLASS - VII

MATTER AND CHANGES IT UNDERGOES

Element : Molecules made of identical atoms are called elements.

Scientists have discovered 105 elements so far. They exist in three states.They are solids, liquids and gases.

Solid State : Sodium, Potassium, Sulphur, Phosphorus.

Liquid State : Hydrogen, Helium, Oxygen, Nitrogen.

Atoms are very active and unstable. Substance having molecules made ofdifferent atoms are called compounds.

The compounds also exist in three states as solids, liquids and gases.

Solid State : Sodium hydroxide, Calcium oxide, calcium carbonate.

Liquid State : Water.

Gaseous state : Carbon dioxide, Sulphur dioxide, Nitrogen peroxide.

Symbols and Formulae :

Element Symbol

Hydrogen H

Oxygen O

Nitrogen N

Carbon C

Fluorine F

Sulphur S

Phosphorus P

Iodine I

Aluminum Al

Bromine Br

Calcium Ca

Chlorine Cl

Barium Ba

Helium He

Magnesium Mg

Manganese Mn

Nickel Ni

Platinum Pt

Silicon Si

Zinc Zn

Element Latin name Symbol

Potassium Kalium K

Sodium Natrium Na

Copper Cuprum Cu

Silver Argentum Ag

Gold Aurum Au

Mercury Hydrargyrum Hg

Lead Plumbum Pb

Tin Stannum Sn

Iron Ferrum Fe

Antimony Stibium Sb

Formulae : Atoms combine together to form molecules. Molecules are alsoindicated by symbols like atoms.

In a molecule there may be two or more atoms of the same element.

In general the first letter of the element is used as its symbol.

Molecules are indicated through symbols.

Valency means the capacity of the atom of the element to combine with thenumber of atoms of Hydrogen. It is also called the combining capacity.

Different elements have different valencies.

Valency is useful in writing molecular formulae.

Physical Changes and Chemical Changes:

A physical change is a temporary change in which only the colour, state of thesubstance changes.

New substance(s) is not formed and no change in composition.

The original substance(s) can be easily obtained after a physical change bysimple methods.

The chemical change is a permanent change is which new substance(s) isformed.

In chemical reactions energy forms like heat, electricity and light are evolvedor absorbed.

Types of Chemical Changes :

Depending on the nature of the chemical reactions the changes are of fourtypes. They are (1) Chemical combination (2) Chemical decomposition (3)Chemical displacement (4) Chemical double decomposition.

The chemical reaction in which two or more substance combine to form a newsubstance is called combination.

In the reaction of combination two elements or two compounds may participate.

The chemical reaction in which a substance decomposes into two or more newsubstances is called decomposition.

The chemical reaction in which an element displaces the element of thecompound is called displacement.

The chemical reaction in which two compounds mutually exchange theirconstituents resulting in the formation of new compounds is called doubledecomposition.

If a chemical change has to take place, heat and electric current are necessary.The conditions under which chemical changes take place differ depending onthe nature of the substance.

Chemical Equations :

Reactants should be written on the left side and products on the right side ofthe arrow mark.

In a chemical reaction the total mass of reactants should be equal to the totalmass of the products. This is based on the law of conservation of mass.Therefore atoms of every element should be adjusted on both sides for correctbalancing.

Gases – Preparation, Properties, Uses:

We can prepare oxygen by heating the chemical substances in which excess ofOxygen is present.

By heating the mixture of Potassium Chlorate and Manganese dioxide, Oxygenis liberated.

Oxygen has no smell.

Oxygen is heavier than air and dissolves in water.

Elements as carbon, Sulphur, Phosphorus burn in Oxygen to form their oxides.Oxygen is supporter of combustion but not combustible.

Metals like Sodium, Potassium, Calcium react with water and release Hydrogengas.

Metals like Zinc and Magnesium react with dilute HCI and release H2 gas.

Hydrogen is a combustible gas but it does not support combustion.

Hydrogen is a colour less gas. Hydrogen is not heaver then air

It does not dissolve in water.

Bi carbonates of sodium or potassium when heated release Carbondioxide.

Hydrogen burns in air, combines with Oxygen and forms water (H2O)

Carbonates of calcium and Lead when heated release CO2 (Carbon dioxide)

Carbon dioxide is a colourless gas with slight smell

Carbon dioxide is heavier than air.

Acids, Bases and Salts

The following three acids are used in the chemical laboratories viz., Hydrochloricacid, Sulphuric acid and Nitric acid.

Acids are sour in taste.

Acids mixed with water are called dilute acids.

Acids react with metals and evolve Hydrogen gas.

Acids decompose carbonates and release carbon dioxide.

Bases are bitter in taste.

Neutralization : Acids and Bases react with each other to form salt and water.This reaction is called Neutralization.