Question

Explain how does nitrogen exhibit anomalous behaviour amongst group $15$ elements.

Answer 1

Anomalous behaviour of nitrogen among group $15$ elements.
Nitrogen is the first amongst group $15$ elements, which has,
(i) The smallest atomic size.
(ii) Highest electronegativity.
(iii) The highest ionisation energy, and
(iv) Absence of d-orbitals.
The difference in the nature between nitrogen and other elements of $15$ grou are:
(i) Nitrogen is a gas while all the other elements are solid.
(ii) Nitrogen exists as diatomic molecule, $\left(N_2\right)$ while other elements exist as tetraatomic molecules($P_4,A{s}_4,S{r}_4$, etc)
(iii) Being the highest electronegativity, nitrogen forms hydrogen bonding while other doesn't.
(iv) Nitrogen forms $p\pi -p\pi$ multiple bonds while other elements in the group from $p\pi -d\pi$ multiple bonds.
(v) Nitrogen shows wide range of oxidation states from $-3$ to $+5$ while other elements show limited oxidation states.
(vi) $N{H}_3$ is basic while other hydrides are very less basic.
(vii)The trihalides of nitrogen(except $N{F}_3$) are unstable while the trihalides of the other elements are comparatively stable.
(viii) Except nitrogen, all other elements have vacant d-orbitals, and due to this nitrogen doesn't undergo formation of coordination compound.