Question

why nitrogen is diatomic while phosphorus is tetra - atomic

Answer 1

Nitrogen is smaller in size hence it forms multiple bonds with other nitrogen and exists as diatomic molecule. Whereas phosphorus atomic size is more so it can form single bond with other phosphorus atoms. Hence it exists as tetra atomic molecule.

@skb

Answer 2

$\huge\textbf{Answer}$


In Nitrogen; small size 2p orbital. So, sideways overlap effectively and make Pπ-Pπ multiple bond. Hence Nitrogen is diatomic.

Whereas in Phosphorus; large sized 3p orbital doesn't effectively overlaps sideways and makes only sigma bond. Hence; Phosphorus is tetratomic.