The general trend in group 15 elements is described as follows:
(i) Oxidation states: The group 15 elements require 3 or more number of electrons to complete their octet and have 5 electrons in their valence shell. It is not easy to gain electrons from some donor as the nucleus will have to attract 3 extra electrons. This occurs only with nitrogen as it is the smallest element in size (in P-block) and the distance between the nucleus and the valence shell is relatively small. The rest of the elements of this group show an oxidation state of -3 in their respective covalent compounds. In addition to the −3 oxidation state, N and P also show -1 and -2 oxidation states respectively. All the elements that are present in this group show +3 and +5 oxidation states. However, the stability of +5 oxidation state decreases while we move down a group, whereas the stability of +5 oxidation state increases accordingly. This occurs due to the inert pair effect.
(ii) Electronic configuration: There are 5 electrons in the valence shell for all the elements in group 15.
Their general electronic configuration is $n{{s}^{2}}n{{p}^{3}}$.
(iii) Electronegativity and Ionization energy:
Ionization enthalpy decreases moving down the group. This occurs due to an increase in the atomic radius. On moving down the group, the electronegativity decreases due to increase in atomic size.
(iv) Atomic size: As we move down the group, the atomic size increases. This increase in
the atomic size is signified by an increase in the number of shells.