Question

Give reason(s) why elemental nitrogen exists as a diatomic molecule whereas elemental phosphorus as a tetraatomic molecule.

Answer 1

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

Answer 2

Answer:

Nitrogen owing to its small size has a tendency to form pπ−pπ multiple bonds with itself.Nitrogen thus forms a very stable diatomic molecule, N 2. On moving down a group, the tendency to form pπ−pπ bonds decreases (because of the large size of heavier elements). Therefore, phosphorus (like other heavier metals) exists in the P 4 state.