Some Exceptional Behavior

Considerable increase in covalent radius from nitrogen to phosphorus but only a small increase from arsenic to bismuth This is due to completely filled d and f orbital's in heavier members.

The ionization energy of group 15 elements is much greater than the group 14elements in corresponding periodThis is due to extra stability of half filled p orbitals

All elements are polyatomic

Nitrogen is gas and all others are solid

Metallic character increases down the group

Except nitrogen all other elements show allotropy

Boiling point increases down the group

Melting point increases up to As and then decreases to Bi

Nitrogen differs from the rest of the members of

its group due to it's small size, high electro

negativity, high ionization enthalpy and non

availability of d-orbital’s.

It has an ability to form pπ-pπ bonds with itself

and hence it is inert at room temperature. Other

elements if its group are singly bonded.

• Towards Hydrogen (H2) forming: EH3 (where E – N, P, As, Sb, Bi)

• Towards Oxygen (O2) forming E2O3 and E2O5 (where E – N, P, As, Sb, Bi)

• Towards Metals exhibits ‘-3’ oxidation state

Preparations:1. Labarotory preparation

NH4Cl(aq) + NaNO2(aq) → N2(g) + NaCl(aq) + 2 H2O (l)

2. thermal decompositon of ammonium dichromate

(NH4)2Cr2O7(s) → Cr2O3(s) + N2(g) + 4 H2O(g)

3. Thermal decomposition of Na or Ba azide

2NaN3 → 2 Na + 3 N2

Colourless, odourless, tasteless, non toxic gas

Low molecular mass, low intermolecular forces

Two stable isotopes

Low solubility in water , low freezing and boiling point

Inert at room temperature due to high bond

᧖ Combination with metals:

6 Li + N2 → 2 Li3N

᧖ Combines with hydrogen (H2): (Haber’s process)

N2 + 3 H2 → 2 NH3 (ΔH = −92.4 kJ·mol−1)

᧖ Formatio of nitric acid (NO)

N2 + O2 → 2 NO

Manufacture of ammonia.

Provide an inert atmosphere in industries.

Used as a refrigerants.

Preparation:o By Haber’s process

N2 + 3 H2 → 2 NH3 (ΔH = −92.4 kJ·mol−1)

o From ammonium salts

Ca(OH)2(s) + 2NH4Cl(s) → CaCl2(s) + 2H2O(l) + 2NH3(g)

o From decay of organic matter

2H2O + NH2CONH2 → (NH4)2 CO3 → 2 NH3 + 4H2O + CO2

• Colourless with pungent odour

• Hydrogen bonding, thus has higher boiling and melting point than expected on the basis of molecular mass

• Structure- trigonal planar

Solubility in water

NH3 + H2O → NH4+ + OH−

Reaction with acids

FeCl3 (aq) + 3NH4OH (aq) → Fe(OH)3 + 3NH4Cl

ZnSO4(aq) + 2 NH4OH(aq) → Zn(OH)2 + (NH4)2(SO4)

• Production of various nitrogenous

fertilizers

• Manufacture of inorganic nitrogen

compounds

• Used as a refrigerants

Oxide Oxidation state characters

N2O nitrogen oxide (nitrous oxide)

+1 Colourless and neutral

NO nitrogen monoxide(nitric oxide)

+2 Colourless and neutral

N2O3 nitrogen trioxide +3 Blue , solid acidic

NO2 nitrogen dioxide +4 Brown, acidic

N2O4 nitrogen tetraoxide +4 Colourless and acidic

N2O5 nitrogen pentaoxide +5 Colourless and acidic

PreparationLaboratory PreparationIt is prepared by heating KmnO3 or NaNO3 and conc. H2SO4 in a glass resort.NaNO3 + H2SO4 → NaHSO4 + HNO3

Industrial PreparationOn large scale it is prepared by Ostwald’sprocess

Step 1 - Catalytic oxidation of NH3 by atmospheric oxygen using Pt as catalyst at 500K and 9 bar pressure

4NH3 + 5O2 → 4NO (g) + 6H2O (g)

Step 2 – Nitric oxide combines with oxygen

2NO (g) + O2 → 2NO2 (g)

Step 3 – Nitrogen dioxide dissolves in water

3NO2(g) + H2O(l) → 2HNO3 (aq) + NO (g)

• Physical PropertiesCommercially available nitric acid is an azeotrope with water at a concentration of 68% HNO3, which is the ordinary concentrated nitric acid of commerce. This solution has a boiling temperature of 120.5 °C at 1 atm. Two solid hydrates are known; the monohydrate (HNO3·H2O) and the trihydrate(HNO3·3H2O).

• Nitric acid 70%• Nitric acid of commercial interest usually consists of

the maximum boiling azeotrope of nitric acid and water, which is approximately 68% HNO3, (approx. 15 molar). This is considered concentrated or technical grade, while reagent grades are specified at 70% HNO3. The density of concentrated nitric acid is 1.42 g/mL. An older density scale is occasionally seen, with concentrated nitric acid specified as 42° Baumé.

1. Reaction with elements less electropositive than hydrogen

Concentrated HNO3

Cu + 4 HNO3 → Cu(NO3)2 + 2 NO2 + 2 H2O

Dilute HNO3

8 HNO3 + 3 Cu → 3 Cu(NO3)2 + 2 NO + 4 H2O

2. Reaction with elements more electropositive than hydrogen

Concentrated HNO3

4 Zn + 10 HNO3 (dilute) → 4 Zn(NO3)2 + N2O + 5 H2O

Dilute HNO3Zn + 4 HNO3 (Conc) → Zn(NO3)2 + 2 NO2 + 2 H2O

3. Some metals donot dissolve in concentration nitric acid because of formation of passive film of oxide of surface.

This test is carried for checking the presence of nitrate ion and it depends on the ability of Fe2+

nitrate to nitric oxide Ferrous sulphate is added to aq. Solution and sulphuric acid is added along the sides of the test tube.

NaNO3 + FeSO4 +H2SO4 → [Fe(H2O)5 (NO)]SO4

Properties White red black

Colour White but yellow on exposure

Dark red Black

State Waxy solid Brittle powder Crystalline

Stability Less stable More stable most stable

Chemical reactivity Very reactive Less reactive Least reactive

Preparation :1. using calcium phosphide with water or dilute HCl

Ca3P2 + 6HCl → + 2PH3

Ca3P2 + 6H2O→ + 2PH32. Laboratory preparation

P4 + 3NaOH + 3H2O (conc. And hot) → PH3 + 3 NaH2PO2

• Colourless gas with rotten fish smell.

• Highly poisonous.

• It explodes in contact with traces of oxidisingagents like HNO3 .

• It is slightly soluble in water.

• It is weakly basic

PH3 + HBr → PH4Br

• Used in Homes signals

• Also used in smoke screens.

The elements of Group 16 have 6 electrons in outermost shell and have ns2 np4 general electronic configuration

• Oxygen: 1s2 2s2 2p4

• Sulphur: 1s2 2s2p6 3s2p4

• Selenium: 1s2 2s2p6 3s2p6d10 4s2p4

• Tellurium: 1s2 2s2p6 3s2p6d10 4s2p6d10 5s2p4

• Polonium: 1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d10 6s2p4

Due to increase in number of shells, atomic and ionic radii increases from top to bottom in group. The size of oxygen atom is exceptionally small.

Ionisation enthalpy of elements of group 16 is lower than group 15 due to half filled p-orbitals in group 15 which are more stable. However, ionization enthalpy decreases down the group.

Oxygen has less negative electron gain

enthalpy than S because of small size of O.

From S to Po electron gain enthalpy becomes less negative to Po

because of increase in atomic size.

Next to fluorine, oxygen has the highest electronegativity value amongst the elements. With in the group, electronegativity decreases with an increase in atomic number. This implies that metallic character increases from oxygen to polonium.

• Oxygen and sulphur are non-metals, selenium and tellurium are metalloids, whereas polonium is a metal.

• All the elements exhibit allotropy.• The melting point and boiling point increase with

an increase in atomic number down the group.• The large difference in melting and boiling point

of oxygen (diatomic) and sulphur (polyatomic) is due to difference in atomicity.

Oxidation states and trends in chemical reactivity1) They show -2, +2, +4, +6 oxidation states. Oxygen does not show

+6 oxidation state due to absence of d –orbitals. Po does not show +6 oxidation state due to inert pair effect.

2) The stability of -2 oxidation state decreases down the group due to increase in atomic size and decrease in electronegativity.

3) Oxygen shows -2 oxidation state in general except in OF2 and O2F2.

4) The stability of +6 oxidation state decreases and +4 oxidation state increases due to inert pair effect.

Anomalous behaviour of oxygen

• The anomalous behaviour of oxygen is due to its small size and high electronegativity.

• The absence of d orbitals in oxygen limits its covalence to four and in practice, rarely exceeds two. On the other hand, in case if other elements of the group, the valence shells can be expanded and covalence exceeds 4.

Reactivity with hydrogenAll group 15 elements from trihydrides, MH3. Hybridisation - sp3

The stability of hydrides decrease down the group due to decrease in

bond dissociation energy down the group.

NH3 > PH3 > AsH3 > SbH3 > BiH3

Boiling point:

PH3 < AsH3 < NH3 < SbH3 < BiH3

Boiling point increases with increase in size due to increase in van der

Waals forces. Boiling point of NH3 is more because of hydrogen bonding.

Bond angle:

NH3 (107.8°) > PH3 (99.5°) > AsH3 (91.8°) ≈ SbH3(91.3°) > BiH3 (90°)

Electronegativity of N is highest. Therefore, the lone pairs will be

towards nitrogen and hence more repulsion between bond pairs.

Therefore bond angle is the highest. After nitrogen, the

electronegativity decreases down the group.

All group 15 elements from trioxides (M2O3) and pentaoxides(M2O5).

Acidic character of oxides decreases and basicity increases down the group. This is because the size of nitrogen is very small. It has a strong positive field in a very small area. Therefore, it attracts the electrons of water’s O-H bond to itself and release H+ ions easily.

As we move down the group, the atomic size increases. Hence, the acidic character of oxides decreases and basicity increases as we move down the group.

Group 15 elements form trihalides and pentahalides. Trihalides – covalent compounds and become ionic down the group. Sp3 hybridisation , pyramidal shape Pentahalides - Sp3d hybridisation, TBP shape They are lewis acids because of the presence of vacant d – orbitals. PCl5 + Cl-→ [PCl6]-

PCl5 is ionic in solid state and exist as [PCl4]+ [PCl6]-

In PCl5, there are three equatorial bonds and two axial bonds. The axial bonds are longer than equatorial bonds because of greater repulsion from equatorial bonds.

It can be obtained in the laboratory by the following ways:- By heating oxygen containing

salts such as chlorates, nitrates, & permanganates.

2KClO3 -----> 2KCl + 3O2

By the thermal decomposition of the oxides of metals low in the electrochemical series & higher oxides of some

metals.2Ag2O ------> 4Ag+ O2

2Pb3O4 --------> 6PbO + O2

Hydrogenperoxide is readily decomposed into water and dioxygen by catalysts such as finely divided metals and

manganese dioxide2H2O2----->2H2O + O2

On large scale it can be prepared from water or air.

Dioxygen is a colourless & odourless gas.

Its solubility in water is to the extent of 3.08cubic cm in 100cubic cm water at 293K which

is just sufficient for the vital support of marine and aquatic life.

It liquefies at 90K and freezes at 55K.

It directly reacts with nearly all metal & non-metals & some noble gases

Its importance in normal respiration.

Combustion processes.

It is used in oxyacetylene welding.

In the manufacture of many metals , particularly steel.

Oxygen cylinders are widely used in hospitals , high altitudes flying and in mountaineering.

For combustion of fuel.

Ozone is an allotropic form of oxygen. It is too reactive to remain for long in atmosphere at sea

level at the height of about 20km.

When a slow dry stream of oxygen is passed through a silent electrical discharge

3O2------> 2O3 = +142 kJ/mol

it is an endothermic process.

If concentration of ozone greater than 10% are required , a battery of ozonisers can be used & pure

ozone (b.p.385K) can be condensed in a vessel surrounded by liquid oxygen.

Pure ozone is a pale blue gas , dark blue liquid & violet-black solid.

Its small concentration is harmless but if concentration rises above 100ppm breathing becomes uncomfortable

resulting in headache and nausea.It is thermodynamically unstable with respect to oxygen.

High concentration of ozone can be dangerously explosive.

It acts as a powerful oxidising agent.PbS + 4O3------->PbSO4 + 4O2

It is used as a germicide, disinfectent, for sterilising water.

It is also used for bleaching oils , ivory, flour , starch,etc.

It acts as an oxidising agent in the manufacture of potassium permanganate.

Sulphur forms numerous allotropes of which the yellow rhombic( alpha-sulphur) & monoclinic ( beta-sulphur) forms are the most important.

It is yellow in colour.

Its m.p. 385.8 K

Specific gravity 2.06.

Its crystals are formed on evaporating the solution of roll sulphur in CS2 .

It is insoluble in water but dissolves to some extent in benzene, alcohol, & ether

It is readily soluble in CS2.

Its melting point is 393K.

Specific gravity is1.98

It is soluble in CS2

It is colourless.

It has needle shaped crystals.

BOTH THE MOLECULES HAVE S8 MOLECULES. THE S8 RING IN BOTH THE FORMS IS PUCKERED AND HAS A

CROWN SHAPE.

Sulphur dioxide is formed together with a little (6-8%) sulphur trioxide when sulphur is burnt in air or

oxygen.S + O2 ------> SO2

In laboratory it is readily generated by treating a sulphitewith dil. Sulphuric acid

It is produced as a bi-product of the roasting of sulphide ores.

4FeS2 + 11O2------>2Fe2O3 + 8SO2

THE GAS AFTER DRYING IS LIQUEFIED UNDER PRESSURE AND STORED IN STEEL CYLINDERS.

Sulphur dioxide is a colourless gas with pungent smell.It is highly soluble in water.

It liquefies at room temperature under 2atm pressure.It boils at 263K.

It reacts readily with NaOH solution, forming sodium sulphite.

2NaOH + SO2------> Na2SO3 + H2OIn its reaction with water and alkalies , the behaviour of

sulphur dioxide is very similar to that of carbon dioxide.

WHEN MOIST, SULPHUR DIOXIDE BEHAVES AS A REDUCING AGENT

2Fe(III) + SO2 + 2H2O-----> 2Fe(II) +SO4(-2) + 4H+

It is used in refining petroleum and sugar.

It is used in bleaching wool and silk.It is used as anti –chlor , disinfectant

and preservative.Liq. SO 2 is used as a solvent to dissolve a

number of organic & inorganic chemicals.

IT IS ONE OF THE MOST IMPORTANT INDUSTRIAL

CHEMICALS WORLDWIDE , THEREFORE IT IS CALLED AS KING

OF CHEMICALS……….!!

Industrially Sulphuric acid is manufactured by CONTACT PROCESS….

The reaction is exothermic , reversible and the forward reaction leads to decrease in volume.

In practice , the plant is operated at a pressure of 2 bar & at temperature 720K.

Dilution of oleum with water gives H2SO4.

THE SULPHURIC ACID OBTAINED BY CONTACT PROCESS IS 96-97% PURE….!!!

It is colourless liquid , dense , oily liquid.It has specific gravity of 1.84 at 298K.

It freezes at 283K & boils at 611K.Concentrated sulphuric acid is a dehydrating

agent.C12H22O11 + H2SO4------> 12C + 11H2O

Hot concentrated sulphuric acid is a moderately strong oxidising agent.

Cu + 2H2SO4(conc.)----> CuSO4 + SO2 + 2H2O3S + 2H2SO4(conc.)-------> 3SO2 + 2H2O

It is used in petroleum refining.

Manufacture of pigments, paints & dyestuff intermediates.

In detergent industry.

Storage batteries.

As a laboratory reagent.

1. Outermost configuration is ns2np5. 2. They have very high ionization enthalpy due to very small atomic

size. The I.E. decreases as we go down the group. 3.They have maximum negative electron gain enthalpy in the

corresponding periods . This is because after gaining an electron they attain the stable noble gas configuration.

However, the negative electron gain enthalpy of fluorine is less than that of chlorine. It is due to small size of fluorine atom. As a result, there are strong interelectronic repulsions in the relatively small 2p orbitals of fluorine and thus, the incoming electron does not experience much attraction.

4. All halogens are coloured. This is due to absorption of radiations in visible region which results in the excitation of outer electrons to higher energy level. For example, F2, has yellow, Cl2 , greenish yellow, Br2, red and I2, violet colour

• 5.The enthalpy of dissociation of F2 is less compared to that of Cl2

• A reason for this anomaly is the relatively large electron-electron repulsion among the lone pairs in F2 molecule due to smaller size of F-atom where they are much closer to each other than in case of Cl2.

• Cl – Cl > Br – Br > I – I.

• Cl2> Br2>F2>I2

Although electron gain enthalpy of fluorine is less negative as compared to chlorine, fluorine is a stronger oxidising agent than chlorine. Why?

Answer :- It is due to

(i) low enthalpy of dissociation of F-F bond

(ii) high hydration enthalpy of F–

1.Fluorine shows only -1 state . due to its high electronegativity. 2. The fluorine atom has no d orbitals in its valence shell and

therefore cannot expand its octet. 3. Others show -1 , +1, +3, +5 and +7. 4. The chemical reactivity decreases down the group, b’coz the

electronegativity decreases. 5. The Oxidising tendency also decreases down the group whereas

the reducing tendency increases. There is a regular decrease in the first ionization energy as we go

down this column. As a result, there is a regular decrease in the oxidizing strength of the halogens from fluorine to iodine. F2 > Cl2 > Br2 > I2

F2 > Cl2 > Br2 > I2

oxidizing strength

1.The order of boiling point is:-

HF > HI> HBr> HCl

HI has exceptionally higher bpt since it forms extensive H-bonding.

The remaining hydrides follow increase in bpt with increase in molar mass.

1. Acidic strength of these acids increases in the order: .

Reason:- BDE decreases.

H–F > H–Cl > H–Br > H–I

2. The stability of these halides decreases down the group

H–F > H–Cl > H–Br > H–I.

1. Fluorine forms two oxides OF2 and O2F2. However, only OF2 is thermally stable at 298 K.

These oxides are essentially oxygen fluorides because of the higher electronegativity of fluorine than oxygen.

Fluorine exhibits only –1 oxidation state whereas other halogens exhibit + 1, + 3, + 5 and + 7 oxidation states also. Explain.

Answer :-

Fluorine is the most electronegative element and cannot exhibit any positive oxidation state. Other halogens have d orbitals and therefore, can expand their octets and show + 1, + 3, + 5 and + 7 oxidation states also.

PreparationLaboratory preparation1. By heating manganese dioxide with concentrates HCl.

MnO2 + 4 HCl ==> MnCl2 + 2 H2O + Cl22. By the action of HCl on potassium permanganate.

2 KMnO4 + 16 HCl ==> 2 MnCl2 + 2 KCl + 8 H2O + 5 Cl2Manufacture of chlorine1. Deacon’s process

By the oxidation of HCl gas by atmospheric oxyden in presence of CuCl2723 k.

2. Electrolytic processChlorine is manufactured industrially as a by-product in the manufacture of

Caustic Soda by the electrolysis of brine. 2 NaCl + 2 H2O ==> Cl2 + H2 + 2 NaOH

Chlorine is

• a highly toxic greenish yellow gas,

• has a pungent odour, and

• fumes in moist air.

Reaction of chlorine with metals

2Al + 3Cl2 ==> 2 AlCl32Na + Cl2 ==> 2NaCl

Reaction with Hydrogen

H2 + Cl2 ==> 2HCl

H2S + Cl2 ==> 2HCl + S

With excess of ammonia, Cl gives nitrogen and ammonium chloride whereas with excess of chlorine it gives nitrogen trichloride (explosive)

8NH3 + 3Cl2 ==> 6NH4Cl + N2

NH3 + 3Cl2 ==> NCl3 + 3HCl

With cold and dilute alkalies chlorine produces a mixture of chloride and hypochlorite but with hot and concentrated alkalies it gives chloride and chlorate

2NaOH + Cl2 ==> NaCl + NaOCl + 3H2O

(Cold and Dilute)

6NaOH + 3Cl2 ==> 5NaCl + NaClO3 + 3H2O

Preparation of Bleaching Powder

2 Cl2 + 2 Ca(OH)2 → Ca(OCl)2 + CaCl2 + 2 H2O

Bleaching action of ChlorineCl water on standing loses its yellow colour due to formation of HCl and HOCl

Bleaching action is due to oxidation.

Cl2 + H2O → 2HCl + O Reaction showing bleaching action of Cl

• for the manufacture of bleaching powder and liquid bleaches,

• to bleach fabrics (e.g. linen and cotton), wood pulp and paper,

• in the manufacture of a wide range of chloro-organic solvents, including Methylene Chloride, CH2Cl2, Chloroform, CHCl3, Carbon Tetrachloride, CCl4,

• in the manufacture of a number of important inorganic chemicals, including Sulphur Chloride, S2Cl2, Thionyl Chloride, SOCl2, Phosgene (i.e. Carbonyl Chloride), COCl2, and inorganic Chlorates, (e.g. Sodium Chlorate, NaClO3),

• as a disinfectant used to kill bacteria in the preparation of drinking water.

• Chlorine is also important in the manufacture of paints, aerosol propellants and plastics.

• for the extraction of Gold from its ores,

PREPARATION

Laboratory methods

1. NaCl + H2SO4 → NaHSO4 + HCl

2. NaCl + NaHSO4 → HCl + Na2SO4

1. It is a colourless and pungent smelling gas.

2. It is easily liquefied and freezes to a white crystalline solid.

3. It is extremely soluble in water.

4. It reacts with NH3 and gives white fumes of NH4Cl.

NH3 + HCl → NH4Cl

5. When 3 parts of concentrated HCl and one part of concentrated HNO3 are mixed aqua regia is formed which is used to dissolve noble metals.

6. HCl decomposes salts of weaker acids.

Na2CO3 + 2HCl 2NaCl + H2O + CO2

Fluorine forms only one oxoacid HOF (Fluoric (I) acid or hypofluorous

acid) due to high electronegativity.

Acid strength: HOCl < HClO2 < HClO3 < HClO4

Reason: HClO4 → H++ ClO4-

Acid strength: HOF > HOCl > HOBr > HOI

This is because Fluorine is most electronegative.

Binary compounds of two different halogen atoms of general formula X X’n are called interhalogen compounds where n = 1, 3, 5, or 7 These are covalent compounds. All these are covalent compounds.Interhalogen compounds are more reactive than halogens because XX’ is a more polar bond than X-X bond. All are diamagnetic. Their melting point is little higher than halogens. XX’ (CIF, BrF, BrCl, ICl, IBr, IF) (Linear shape)XX’3 (CIF3, BrF3, IF3, ICl3) (Bent T- shape) XX’5 – CIF5, BrF5, IF5, (square pyramidal shape) XX’7 – IF7 (Pentagonal bipyramidal shape)

• 1.Group 18 consists of six elements: helium, neon, argon, krypton, xenon and radon.

• 2.Electronic configuration is ns2np6

• 3.They have very high ionization enthalpy due to stable configuration.

• 4..All these are gases and chemically unreactive. They form very few compounds. Because of this they are termed noble gases.

• 5.All the noble gases except radon occur in the atmosphere. Their atmospheric abundance in dry air is ~ 1% by volume of which argon is the major constituent.

Helium and sometimes neon are found in minerals of radioactive origin e.g., pitchblende, monazite, cleveite. The main commercial source of helium is natural gas. Xenon and radon are the rarest elements of the group. 6.They have very low melting and boiling points because the interatomic interaction in these elements is weak dispersion forces. Helium has the lowest boiling point (4.2 K) of any known substance. It has an unusual property of diffusing through most commonly used laboratory materials such as rubber, glass or plastics.

• 7.In general, noble gases are least reactive. Their inertness to chemical reactivity is attributed to the following reasons:

• (i) The noble gases except helium (1s2) have completely filled ns2np6 electronic configuration in their valence shell.

• (ii) They have high ionisation enthalpy and more positive electron gain enthalpy.(since they do not have any tendency to accept an additional electron as their outermost orbits are completely filled)

8.Xenon has lower ionisation enthalpy, because of large size of xenon. 9. Xenon reacts with only oxygen and fluorine atoms because these two elements are of very high polarizing capacity. 10.The fact that the first IE of xenon is comparable with that of molecular oxygen prompted Neil Bartlett to study the chemistry of xenon compounds.(he understood this from the compound O2PtF6, which he prepared ) The first compound of xenon prepared was XePtF6

• Why are the elements of Group 18 known as noble gases ?

The elements present in Group 18 have their valence shell orbitals completely filled and, therefore, react with a few elements only under certain conditions. Therefore, they are known as noble gases.

• Xenon forms three binary fluorides, XeF2, XeF2 and XeF6 by the direct reaction of elements under appropriate experimental conditions.

• XeF6 can also be prepared by the interaction of XeF4 and O2F2 at 143K.

• XeF4 + O2 F2 XeF6 + O2

1.XeF2 is hydrolysed to give Xe, HF and O2.

2XeF2 (s) + 2H2O(l)2Xe (g) + 4 HF(aq) + O2(g)

2.Xenon fluorides react with fluoride ion acceptors to form cationic species and fluoride ion donors to form fluoroanions.

Hydrolysis of XeF4 and XeF6 with water gives XeO3.

6XeF4 + 12 H2O 4Xe + 2XeO3 + 24 HF + 3 O2

XeF6 + 3 H2O XeO3 + 6 HF

1.Helium is a non-inflammable and light gas. Hence, it is used in filling balloons for meteorological observations. It is also used in gas-cooled nuclear reactors. Liquid helium (b.p. 4.2 K) finds use as cryogenic agent for carrying out various experiments at low temperatures. It is used to produce and sustain powerful superconducting magnets which form an essential part of modern NMR spectrometers and Magnetic Resonance Imaging (MRI) systems for clinical diagnosis. It is used as a diluent for oxygen in modern diving apparatus because of its very low solubility in blood.

.

2.Neon is used in discharge tubes and fluorescent bulbs for advertisement display purposes. 3.Argon is used mainly to provide an inert atmosphere in high temperature metallurgical processes (arc welding of metals or alloys) and for filling electric bulbs. It is also used in the laboratory for handling substances that are air-sensitive. 4.Xenon and Krypton are used in light bulbs designed for special purposes

Compiled andpresented by

Kush Sehgal r.no 29Lakshay Thakur r.no 30Mamik Dutta r.no 31Manisha Dash r.no 32Mayank Kashyap r.no