Groups 5A – 8A. Group 5A Nitrogen and phosphorus are non-metals, arsenic is a semimetal, and...

Groups 5A – 8AGroups 5A – 8A

Group 5AGroup 5A

Nitrogen and phosphorus are non-Nitrogen and phosphorus are non-metals, arsenic is a semimetal, and metals, arsenic is a semimetal, and antimony and bismuth tend to be antimony and bismuth tend to be metallic, typically forming ions with a metallic, typically forming ions with a +3 charge.+3 charge.

The oxides of nitrogen and The oxides of nitrogen and phosphorus are acidic when dissolved in phosphorus are acidic when dissolved in water. Arsenic and antimony oxides are water. Arsenic and antimony oxides are amphoteric, and bismuth oxide is basic.amphoteric, and bismuth oxide is basic.

Group 5AGroup 5A

The elements of group 5A may form The elements of group 5A may form three, five or six covalent bonds, except three, five or six covalent bonds, except for nitrogen which cannot expand its for nitrogen which cannot expand its “octet.”“octet.”

Due to its small size, nitrogen readily Due to its small size, nitrogen readily forms forms ππ bonds. Thus elemental nitrogen, bonds. Thus elemental nitrogen, NN22, has a triple bond. The other elements , has a triple bond. The other elements exist as larger molecules containing exist as larger molecules containing single bonds.single bonds.

NitrogenNitrogen

Elemental nitrogen is an Elemental nitrogen is an extremely stable molecule due to the extremely stable molecule due to the triple bond. As a result, many triple bond. As a result, many nitrogen containing compounds nitrogen containing compounds decompose exothermically (and decompose exothermically (and sometimes explosively) to form sometimes explosively) to form nitrogen gas.nitrogen gas.

ExplosivesExplosives

Nitrogen based Nitrogen based explosives such as explosives such as nitroglycerin, will nitroglycerin, will rapidly decompose rapidly decompose when ignited or when ignited or exposed to a sudden exposed to a sudden impact.impact.


C3H5(NO3)3(l) 6 N2(g) + 12CO2(g) + 12H2O(g) + O2(g) + energy

Note the large number of moles of gaseous products. Explosives typically involve a very large volume change, producing many moles of small gaseous molecules.


Trinitrotoluene, TNT, is another nitrogen based explosive.

2C7H5(NO3)3(l) 12 CO2(g) + 5 H2(g) + 3N2(g) + 2C(s) + energy

Sodium AzideSodium Azide

Sodium Sodium azide, NaNazide, NaN33(s), is (s), is used in air bags used in air bags in automobiles. in automobiles. A small amount A small amount of sodium azide of sodium azide (100g) yields 56L (100g) yields 56L of nitrogen gas at of nitrogen gas at 2525ooC and 1 atm.C and 1 atm.

Sodium AzideSodium Azide

NaNNaN33((ss) ) 2Na( 2Na(ll) + 3 H) + 3 H22((gg))

This reaction takes place in about 40ms. This reaction takes place in about 40ms. Other components are put in the air bag Other components are put in the air bag so that the molten sodium metal is so that the molten sodium metal is deactivated into glassy silicates.deactivated into glassy silicates.

10 Na(10 Na(ll) +2KNO) +2KNO33((ss) ) KK22O(O(ss) +5Na) +5Na22O(O(ss)+ )+ NN22((gg))

2 K2 K22O(O(ss) + SiO) + SiO22((ss) ) K K44SiOSiO44((ss))

2 Na2 Na22O(O(ss) + SiO) + SiO22((ss) ) Na Na44SiOSiO44((ss))

Nitrogen FixationNitrogen FixationBacteria (in the Bacteria (in the nodules on the roots of nodules on the roots of pea plants) can readily pea plants) can readily convert nitrogen to convert nitrogen to ammonia at 1 atm and ammonia at 1 atm and soil temperature.soil temperature.

The The Haber process Haber process requires a temperature requires a temperature of 400of 400ooC and a C and a pressure of 250 atm.pressure of 250 atm.

Uses of Nitrogen Uses of Nitrogen CompoundsCompounds

Ammonia, synthesized from nitrogen Ammonia, synthesized from nitrogen and hydrogen using the and hydrogen using the HaberHaber process, is process, is used to make fertilizers, explosives and used to make fertilizers, explosives and nitric acid.nitric acid.

Dinitrogen oxide, NDinitrogen oxide, N22O, is used as O, is used as “laughing gas”, a dental anesthetic. The “laughing gas”, a dental anesthetic. The gas is highly soluble in fats, and its major gas is highly soluble in fats, and its major use is as a propellant in cans of whipped use is as a propellant in cans of whipped cream.cream.

Uses of Nitrogen Uses of Nitrogen CompoundsCompounds

Nitrogen monoxide, NO, is a Nitrogen monoxide, NO, is a biologically active molecule, and is biologically active molecule, and is crucial in controlling blood pressure crucial in controlling blood pressure and the dilation of blood vessels.and the dilation of blood vessels.

Environmental IssuesEnvironmental Issues

Nitrogen dioxide (NONitrogen dioxide (NO22) and ) and dinitrogen tetra-oxide (Ndinitrogen tetra-oxide (N22OO44) are in ) are in equilibrium with each other:equilibrium with each other:

NN22OO44((gg) ↔ 2 NO) ↔ 2 NO22((gg))

colorlesscolorless red-brown red-brown

The oxides of nitrogen are the result The oxides of nitrogen are the result of high temperature combustion in jet of high temperature combustion in jet engines and automobiles.engines and automobiles.

Environmental IssuesEnvironmental Issues

The compounds cause the reddish The compounds cause the reddish brown smog seen over Los Angeles brown smog seen over Los Angeles and other cities on a sunny day. They and other cities on a sunny day. They also react with moisture in the air to also react with moisture in the air to produce nitric acid and nitrous acid.produce nitric acid and nitrous acid.

This “acid rain” is a respiratory This “acid rain” is a respiratory irritant, and destroys facades of irritant, and destroys facades of buildings and statuary.buildings and statuary.

Isolation of PhosphorusIsolation of Phosphorus

Phosphorus Phosphorus was initially was initially isolated in an isolated in an attempt to extract attempt to extract gold from urine.gold from urine.

The element The element emits light and emits light and glows when glows when exposed to exposed to oxygen.oxygen.

PhosphorusPhosphorus

Elemental phosphorus exists as Elemental phosphorus exists as several allotropes. All differ greatly several allotropes. All differ greatly in structure from nitrogen due to a in structure from nitrogen due to a lack of multiple bonding between the lack of multiple bonding between the larger phosphorus atoms. larger phosphorus atoms. Phosphorous can also use Phosphorous can also use dd orbitals orbitals to expand its bonding.to expand its bonding.

Elemental PhosphorusElemental Phosphorus

white

phosphorus

black

phosphorus

red

phosphorus

Elemental PhosphorusElemental Phosphorus

White PhosphorusWhite Phosphorus

White phosphorus White phosphorus exists as discrete Pexists as discrete P44 molecules. It is a molecules. It is a waxy white solid that waxy white solid that is very poisonous is very poisonous and reactive. It and reactive. It burns vigorously in burns vigorously in air, and is stored air, and is stored under water.under water.

White PhosphorusWhite Phosphorus

The element gets its name from The element gets its name from the phosphorescent glow emitted by the phosphorescent glow emitted by white phosphorus when it is exposed white phosphorus when it is exposed to air in the dark.to air in the dark.

White phosphorus has been White phosphorus has been used in weaponry. The pieces of used in weaponry. The pieces of phosphorus in bombs and grenades phosphorus in bombs and grenades get embedded in the skin, where get embedded in the skin, where they burn.they burn.

Red PhosphorusRed Phosphorus

Red Phosphorus is a polymeric chain of PRed Phosphorus is a polymeric chain of P44 units. It is stable in air to a temperature units. It is stable in air to a temperature of 400of 400ooC. Red phosphorus is used in C. Red phosphorus is used in “safety” matches on the striking surface.“safety” matches on the striking surface.

Red PhosphorusRed Phosphorus

Red phosphorus is used in “safety” Red phosphorus is used in “safety” matches on the striking surface.matches on the striking surface.

Black PhosphorusBlack Phosphorus

Black phosphorus is the most Black phosphorus is the most stable of the allotropes. It is formed stable of the allotropes. It is formed from white phosphorus that is from white phosphorus that is heated under very high pressures.heated under very high pressures.

Source of PhosphorusSource of Phosphorus

Phosphorus must be extracted from Phosphorus must be extracted from its compounds, as it is not found in its compounds, as it is not found in elemental form. The main source is elemental form. The main source is phosphate rockphosphate rock, or calcium phosphate. , or calcium phosphate. Large deposits are found in central Large deposits are found in central Florida, Morocco and the Pacific island Florida, Morocco and the Pacific island of Nauru.of Nauru.

The extraction process consumes The extraction process consumes large amounts of electricity and coke, large amounts of electricity and coke, and produces large amounts of dusts, and produces large amounts of dusts, flue gases and sludge.flue gases and sludge.

Uses of Phosphorus Uses of Phosphorus CompoundsCompounds

Phosphates are used in fertilizers, Phosphates are used in fertilizers, and the salt of tripolyphosphoric acid is and the salt of tripolyphosphoric acid is used in detergents that won’t form used in detergents that won’t form insoluble “scum” in hard water.insoluble “scum” in hard water.

Phosphoric acid is added to soft Phosphoric acid is added to soft drinks where it prevents bacterial drinks where it prevents bacterial growth and also forms inert compounds growth and also forms inert compounds with any metal ions that may be leached with any metal ions that may be leached from the container walls.from the container walls.

Biological Aspects - Biological Aspects - NitrogenNitrogen

All plant life requires nitrogen All plant life requires nitrogen for growth and survival. Bacteria for growth and survival. Bacteria found in nodules on the roots of pea, found in nodules on the roots of pea, bean, alder and clover plants bean, alder and clover plants convert nitrogen in the air to convert nitrogen in the air to nitrogen compounds. nitrogen compounds.

Biological Aspects - Biological Aspects - PhosphorusPhosphorus

Phosphorus is essential for life. Phosphorus is essential for life. The hydrogen phosphate ion and The hydrogen phosphate ion and dihydrogen phosphate ions are dihydrogen phosphate ions are involved in buffering blood. involved in buffering blood. Phosphate units link the sugar esters Phosphate units link the sugar esters of DNA and RNA, and also make up of DNA and RNA, and also make up part of ATP, the energy storage unit part of ATP, the energy storage unit in living things. in living things.

Biological Aspects - Biological Aspects - ArsenicArsenic

Arsenic, though generally Arsenic, though generally considered toxic, is also essential to considered toxic, is also essential to life. We only need trace amounts, life. We only need trace amounts, and its role is still unknown. and its role is still unknown.

In the 19In the 19thth century, before the century, before the discovery of antibiotics, arsenic was discovery of antibiotics, arsenic was used as one of the first forms of used as one of the first forms of chemotherapy to destroy the chemotherapy to destroy the organism that causes syphilis.organism that causes syphilis.

The group 6A ElementsThe group 6A Elements

Group 6A, oxygen, sulfur, selenium , Group 6A, oxygen, sulfur, selenium , tellurium and polonium, are sometimes tellurium and polonium, are sometimes called the called the chalcogenschalcogens. O, S and Se are . O, S and Se are nonmetals, Te a semimetal, and nonmetals, Te a semimetal, and polonium the only metal of the group.polonium the only metal of the group.

Except for oxygen, the other members Except for oxygen, the other members of the group exhibit all even-numbered of the group exhibit all even-numbered oxidation states from -2 through zero oxidation states from -2 through zero to +6.to +6.

OxygenOxygen

Oxygen contains a double bond Oxygen contains a double bond that is much stronger than a single that is much stronger than a single bond (494 kJ/mol vs. 142 kJ/mol). bond (494 kJ/mol vs. 142 kJ/mol). The lower elements in the group The lower elements in the group form much weaker form much weaker ππ bonds due to bonds due to their larger atomic size and greater their larger atomic size and greater bond length.bond length.

OxygenOxygen

Oxygen is a colorless, odorless Oxygen is a colorless, odorless gas that forms a pale blue liquid. gas that forms a pale blue liquid. The molecule is The molecule is paramagneticparamagnetic due to due to the presence of two unpaired the presence of two unpaired electrons, and is attracted to a electrons, and is attracted to a magnetic field.magnetic field.

OzoneOzone

Ozone, OOzone, O33, is an allotrope of , is an allotrope of oxygen. It occurs naturally in the oxygen. It occurs naturally in the upper atmosphere of earth. The upper atmosphere of earth. The ozone layerozone layer absorbs ultraviolet light absorbs ultraviolet light and serves to help screen out and serves to help screen out harmful, cancer causing, radiation.harmful, cancer causing, radiation.

SulfurSulfurSulfur is found Sulfur is found

in large deposits as in large deposits as the free element, the free element, or in a variety of or in a variety of ores. Elemental ores. Elemental sulfur has a variety sulfur has a variety of forms and of forms and structures. At structures. At room temperature, room temperature, the most stable the most stable form is rhombic form is rhombic sulfur, Ssulfur, S88 rings. rings.

SulfurSulfur

If molten sulfur is cooled slowly, If molten sulfur is cooled slowly, the eight- membered rings stack into the eight- membered rings stack into monoclinic sulfurmonoclinic sulfur, which has a , which has a needle-like appearance.needle-like appearance.

The Frasch ProcessThe Frasch Process

The Frasch process is used to extract The Frasch process is used to extract sulfur from underground deposits. sulfur from underground deposits. Superheated water (under pressure) is Superheated water (under pressure) is pumped into the ground where the pumped into the ground where the sulfur melts. The molten sulfur is then sulfur melts. The molten sulfur is then pumped up to the surface and into huge pumped up to the surface and into huge forms where it cools and solidifies. forms where it cools and solidifies. Explosives are used to break the huge Explosives are used to break the huge chunks of sulfur into more useable chunks of sulfur into more useable sizes.sizes.

The Frasch ProcessThe Frasch Process

Sulfur OxidesSulfur Oxides

Sulfur dioxide and sulfur Sulfur dioxide and sulfur trioxide are formed during the trioxide are formed during the combustion of sulfur-containing fuels combustion of sulfur-containing fuels (coal). They are respiratory (coal). They are respiratory irritants, and, when combined with irritants, and, when combined with moisture in the air, produce moisture in the air, produce acid acid rainrain..

SeleniumSelenium

Until the 1960s, the only major Until the 1960s, the only major use of selenium was the addition of use of selenium was the addition of CdSe to glass to produce a ruby-red CdSe to glass to produce a ruby-red color. Cadmium selenide is also color. Cadmium selenide is also used as a semiconductor in used as a semiconductor in photocells, because its conductivity photocells, because its conductivity varies with light intensity.varies with light intensity.

SeleniumSelenium

Selenium is now used in “xerox” Selenium is now used in “xerox” machines and laser printers. They use machines and laser printers. They use a drum coated with selenium that is a drum coated with selenium that is exposed to an electric field. The exposed to an electric field. The regions on the drum that are exposed regions on the drum that are exposed to high light intensity lose their charge. to high light intensity lose their charge. Toner powder adheres only to the Toner powder adheres only to the charged areas of the drum which charged areas of the drum which correspond to the printed areas on the correspond to the printed areas on the page.page.

PhotocopiersPhotocopiers

The Halogens – Group 7AThe Halogens – Group 7A

Group 7AGroup 7A

Group 7A is the first group that Group 7A is the first group that consists of all non-metals. Fluorine, consists of all non-metals. Fluorine, chlorine, bromine and iodine all exist chlorine, bromine and iodine all exist as diatomic molecules at room as diatomic molecules at room temperature. Astatine, At, is temperature. Astatine, At, is unstable, and very rare.unstable, and very rare.

The elements illustrate a variety The elements illustrate a variety of group trends.of group trends.

Group 7AGroup 7A

Group 7AGroup 7A

The halogens are typically found The halogens are typically found in ionic form. The elements are in ionic form. The elements are prepared by electrolysis of salts (for prepared by electrolysis of salts (for F2 and Cl2) or using redox reactions. using redox reactions.

FluorineFluorine

Fluorine is the most Fluorine is the most electronegative element, and often electronegative element, and often acts as an oxidizing agent. Fluorine acts as an oxidizing agent. Fluorine exhibits oxidation numbers of zero exhibits oxidation numbers of zero and -1 only. The other halogens and -1 only. The other halogens have positive oxidation numbers have positive oxidation numbers when bonded to fluorine or oxygen.when bonded to fluorine or oxygen.

FluorineFluorine

Fluorine has only one isotope, Fluorine has only one isotope, 1919F. FF. F22((gg) is used to separate ) is used to separate isotopes of uranium. Uranium exists isotopes of uranium. Uranium exists as two isotopes, as two isotopes, 238238U and U and 235235U. U. Uranium-235 is used in bombs and Uranium-235 is used in bombs and nuclear reactors. Both isotopes of nuclear reactors. Both isotopes of uranium are found in deposits as uranium are found in deposits as UOUO22(s). (s).

FluorineFluorine

The uranium (IV) oxide is The uranium (IV) oxide is converted to the fluoride using converted to the fluoride using HF(HF(gg). ).

UOUO22((ss) + 4 HF() + 4 HF(gg) ) UF UF44((ss) + 2 ) + 2 HH22O(O(gg))

FluorineFluorine

The ionic UFThe ionic UF44 is reacted with is reacted with fluorine gas to form covalent (and fluorine gas to form covalent (and gaseous at 60gaseous at 60ooC) UFC) UF66..

UFUF44((ss) + 2 F) + 2 F22 ( (gg)) UF UF66(g)(g)

The gaseous mixture of The gaseous mixture of 235235UFUF6 6 and and 238238UFUF6 6 can be separated based on their can be separated based on their different rates of effusion.different rates of effusion.

Hydrofluoric AcidHydrofluoric Acid

HF(HF(aqaq), is a weak acid, whereas ), is a weak acid, whereas the binary acids of the other the binary acids of the other halogens are all strong acids. HF halogens are all strong acids. HF has another unique property. It can has another unique property. It can be used to etch glass, and must be be used to etch glass, and must be stored in plastic bottles.stored in plastic bottles.

Hydrofluoric AcidHydrofluoric Acid

SiOSiO22((ss) +6 HF() +6 HF(aqaq)) SiF SiF662-2-((aqaq) + 2 H) + 2 H++

((aqaq) + ) +

2 H2 H22O(O(ll))

Fluoridation of WaterFluoridation of Water

The enamel of teeth contains The enamel of teeth contains hydroxyapatite, Cahydroxyapatite, Ca55(PO(PO44))33(OH). The (OH). The compound is somewhat soluble in compound is somewhat soluble in the acidic media of the mouth. If the the acidic media of the mouth. If the hydoxide ion is replaced with hydoxide ion is replaced with fluoride, the less soluble and harder fluoride, the less soluble and harder fluorapetite, Cafluorapetite, Ca55(PO(PO44))33(F) is formed. (F) is formed. The harder enamel resists decay. The harder enamel resists decay.

ChlorineChlorine

Chlorine is a pale green Chlorine is a pale green poisonous gas, and was used as the poisonous gas, and was used as the first poison gas in warfare. In small first poison gas in warfare. In small doses, chlorine gas effectively kills doses, chlorine gas effectively kills harmful bacteria in drinking and harmful bacteria in drinking and swimming water.swimming water.

BromineBromine

Bromine is a volatile, oily, Bromine is a volatile, oily, orange-brown corrosive liquid at orange-brown corrosive liquid at room temperature. Silver bromide, room temperature. Silver bromide, AgBr(s), is used in black and white AgBr(s), is used in black and white photography. Upon exposure to photography. Upon exposure to light, the silver ion forms fine light, the silver ion forms fine crystals of metallic silver.crystals of metallic silver.

IodineIodine

Iodine is a dark purple metallic Iodine is a dark purple metallic looking solid. In the human body, it is looking solid. In the human body, it is found primarily in the thyroid gland found primarily in the thyroid gland where if is used in the synthesis of the where if is used in the synthesis of the hormones thyroxine and hormones thyroxine and triiodothyronine. triiodothyronine. These These hormones are essential for growth, the hormones are essential for growth, the regulation of neuromuscular functions, regulation of neuromuscular functions, and the maintenance of reproductive and the maintenance of reproductive functions.functions.

Group 8A – The Noble Group 8A – The Noble GasesGases


It was believed that the noble It was believed that the noble gases, He, Ne, Ar, Kr, Xe and Rn, gases, He, Ne, Ar, Kr, Xe and Rn, were inert, and never formed were inert, and never formed compounds. During the past 50 compounds. During the past 50 years, several compounds of Kr, Ze years, several compounds of Kr, Ze and Rn have been synthesized. and Rn have been synthesized.

The Discovery of the Noble The Discovery of the Noble GasesGases

It had been known since at least It had been known since at least 1785 that air contained something in 1785 that air contained something in addition to oxygen and nitrogen. addition to oxygen and nitrogen. The new elements was called The new elements was called argonargon, , from the Greek word for “lazy.”from the Greek word for “lazy.”

Helium was identified in the Helium was identified in the emission spectrum of the sun (1868) emission spectrum of the sun (1868) before it was isolated on earth from before it was isolated on earth from uranium ores.uranium ores.

Group TrendsGroup Trends

All elements are odorless, All elements are odorless, colorless monatomic gases at room colorless monatomic gases at room temperature. The boiling points temperature. The boiling points are consistent with weak london are consistent with weak london dispersion forces and the increase in dispersion forces and the increase in polarizability going down the group.polarizability going down the group.

Uses of the Noble GasesUses of the Noble Gases

Helium, due to its low density Helium, due to its low density and chemical inertness, is used to and chemical inertness, is used to provide lift for baloons and blimps.provide lift for baloons and blimps.

Helium is also used in breathing Helium is also used in breathing mixtures for deep sea diving. It is mixtures for deep sea diving. It is less soluble in the blood than less soluble in the blood than nitrogen, and thus minimizes “the nitrogen, and thus minimizes “the bends.”bends.”

Uses of Noble GasesUses of Noble Gases

Argon is chiefly used to provide Argon is chiefly used to provide an inert atmosphere for chemical an inert atmosphere for chemical reactions and in welding. Along reactions and in welding. Along with Ne, Kr and Xe, argon also with Ne, Kr and Xe, argon also produces characteristic colors in produces characteristic colors in “neon” lights. Argon is also used “neon” lights. Argon is also used between panes of glass in thermal between panes of glass in thermal insulating windows.insulating windows.

Compounds of Xe and KrCompounds of Xe and Kr

The first compound of a noble The first compound of a noble gas, XePtFgas, XePtF66(s), was synthesized in (s), was synthesized in the early 1960s using a very strong the early 1960s using a very strong oxidizing agent, PtFoxidizing agent, PtF66(g).(g).

Since then, several compounds Since then, several compounds containing Xe or Kr with fluorine containing Xe or Kr with fluorine and oxygen have been synthesized. and oxygen have been synthesized.

RadonRadon

Radon is radioactive, and is formed Radon is radioactive, and is formed in rocks and soil by the radioactive in rocks and soil by the radioactive decay of uranium and thorium. decay of uranium and thorium. 222222Rn Rn can infiltrate the air in basements. can infiltrate the air in basements. Since it is gaseous, it is breathed into Since it is gaseous, it is breathed into the lungs where it undergoes the lungs where it undergoes radioactive decay, bombarding lung radioactive decay, bombarding lung tissue with alpha and beta particles. tissue with alpha and beta particles. These particles disrupt living cells and These particles disrupt living cells and can initiate lung cancer.can initiate lung cancer.

Groups 5A – 8A. Group 5A Nitrogen and phosphorus are non-metals, arsenic is a semimetal, and...

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Transcript of Groups 5A – 8A. Group 5A Nitrogen and phosphorus are non-metals, arsenic is a semimetal, and...