Question

Nitrogen cannot form a pentahalide. Explain.

Answer 1

Formation of pentahalides requires $s{p}^{3}d$ hybridization of central atom. This can be obtained by transfer of electrons from central atom to empty d-orbitals in excited stae.

As nitrogen has no d-orbital in its valence shell, it cannot undergoes $s{p}^{3}d$ hybridization and hence cannot form pentahalides

On the other hand, Phosphorous has vacant d-orbitals in its valence shell and an electron from 3s orbital can be exited to vacant d-orbitals giving $5s{p}^{3}d$ hybride orbitals and hence it is able to form $PC{l}_5$