Nitrogen produces only `NCl_(3)` but phosphorus produces both `PCl_(3)` and `PCl_(5)`. Give reasons.

Explanation

The valence shell electronic configurations of nitrogen and phosphorus are as follows:

both nitrogen and phosphorus contain 3 unpaired electrons in their valence shells. Using these unpaired electrons, they can form three covalent bonds with chlorine. in this way, `NC l_(3) and PC l_(3)` are produced. due to the presence of vacant 3d-robital in phosphorus, one 3s-elecrtorn can be promoted to 3d-orbital and the five unpaired electrons thus obtained can form five covalent bonds with five chlorine atoms to produce `PCl_(5)`. on the other hand, nitrogen has no d-orbital in its second shell. unlike phosphorus it cannot extend its covalency to five and hence, it cannot produce `NC l_(5)`.