Discuss the general characteristics of Group-15 elements with reference to their electronic configuration, oxidation state, atomic size, ionisation enthalpy and electronegativity.

Explanation

(i) Electronic configuration : General electronic configuration is nsz np3. These elements have five electrons in valance shell.
(ii) Oxidation states : The common oxidation states of Group-15 elements are (-3), (+3) and (+5). The stability of elements in (+5) oxidation state decreases down the group due to inert pair effect. The phosphorus disproportionates in all intermediate states from (-3) to (+5) while nitrogen disproportionates in (+3) oxidation state.
(iii) Atomic size : Down the group, the atomic radii of these elements increases. However, there is small increase in radii from As to Bi due to presence of completely filled d- or f-orbitals.
(iv) Ionisation enthalpy : As compared to group-14 and group-16 elements, group-15 elements have high values of ionisation enthalpies due to half filled valance orbitals. Down the group, ionisation enthalpy decreases but difference in ionisation enthalpies of heavier members is not so significant.