Question

Explain the following: 
(i) NCl\(_3\) occurs but NCl\(_5\) does not. Why? 
(ii) Why are halogens strong oxidising agents? 
 

Hint:

NCl\(_5\) cannot form as nitrogen lacks d-orbitals; halogens are strong oxidisers due to high electron affinity.

Answer 1

(i) Explanation.
Nitrogen has only \(2s\) and \(2p\) orbitals, no vacant d-orbitals. Therefore, nitrogen cannot expand its octet to form NCl\(_5\). But phosphorus (in PCl\(_5\)) can, due to vacant 3d orbitals. Hence only NCl\(_3\) exists.
(ii) Explanation.
Halogens have high electronegativity and very high electron affinity. They readily accept electrons to form halide ions, making them strong oxidising agents.