Question

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

Answer 1

(1) Electronic configuration
Group 15 elements have 5 valence electrons with general electronic configuration $n{s}^{2}n{p}^3$.

(2) Oxidation state
They have 5 valence electrons and to complete octet, they need 3 more electrons. This is difficult. Only N can do this as it has small size. Other elements show a formal oxidation state of -3 in covalent compounds. N, P show, -1 and -2 oxidation states apart from -3 oxidation state. All elements shows +3 and +5 oxidation states and the stability of +5 oxidation state decreases down a group and that of +3 oxidation state increases due to inert pair effect.
(3) Atomic size
With increase in the atomic number, the atomic size increases due to increase in the number of shells.
(4) Ionisation enthalpy
On moving down the group, first ionization energy decreases due to increase in size.
(5) Electronegativity
On moving down the group, electronegativity decreases due to increase in size.