. Group (Nitrogen group) elements: . . Occurrence: About % of earth atmosphere contains dinitrogen (N ) gas.
It is also present in earth crust as sodium nitrate (Chile saltpetre) and potassium nitrate (Indian saltpetre). The 11th most abundant element phosphorus, exists as phosphate (fluroapatite, chloroapatite and hydroxyapatite). The other elements arsenic, antimony and bismuth are present as sulphides and are not very abundant. .
. Physical properties: Some of the physical properties of the group elements are listed below Table . Physical properties of group elements Property Nitrogen Phosphorus Arsenic Antimony Bismuth Physical state at K Gas Solid Solid Solid Solid Atomic Number Isotopes N, N P As Sb Bi Atomic Mass (g.mol - at K) . .
. . Electronic configuration [He]2s 2p [Ne]3s 3p [Ar]3d 4s 4p [Kr]4d 5s 5p [Xe] 4f 5d 6s 6p Atomic radius (Å) . .
. . . Density (g.cm - at K) .
x - . (white phosphorus) . . .
Melting point (K) Sublimes at Boiling point (K) . . Nitrogen: Preparation: Nitrogen, the principal gas of atmosphere ( % by volume) is separated industrially from liquid air by fractional distillation Pure nitrogen gas can be obtained by the thermal decomposition of sodium azide about K 2NaN Na + 3N XII XII - - - - It can also be obtained by oxidising ammonia using bromine water 8NH + 3Br 6NH Br + N Properties Nitrogen gas is rather inert. Terrestrial nitrogen contains .
% and . % of nitrogen- and nitrogen- respectively. The later is used for isotopic labelling. The chemically inert character of nitrogen is largely due to high bonding energy of the molecules cal mol - ( kJ mol - ).
Interestingly the triply bonded species is notable for its less reactivity in comparison