(i) Electronic configuration: All the elements in group 15 have 5 valence electrons. Their general electronic configuration is ns2 np3.
(ii) Oxidation states: All these elements have 5 valence electrons and require three
more electrons to complete their octets. However, gaining electrons is very difficult
as the nucleus will have to attract three more electrons. This can take place only with
nitrogen as it is the smallest in size and the distance between the nucleus and the
valence shell is relatively small. The remaining elements of this group show a formal oxidation state of −3 in their covalent compounds. In addition to the −3 state, N and P also show −1 and −2 oxidation states.
All the elements present in this group show +3 and +5 oxidation states. However, the
stability of +5 oxidation state decreases down a group, whereas the stability of +3
oxidation state increases. This happens because of the inert pair effect.
(iii) Ionization energy and electronegativity
First ionization decreases on moving down a group. This is because of increasing atomic
sizes. As we move down a group, electronegativity decreases, owing to an increase in size.
(iv) Atomic size: On moving down a group, the atomic size increases. This increase in
the atomic size is attributed to an increase in the number of shells.
