Nitrogen is diatomic but phosphorus is tetra-atomic. Why?

Question

Nitrogen is diatomic but phosphorus is tetra-atomic. Why?

Answer 1

Due to larger atomic size P is unable to form pi bonds and so it is tetra-atomic in which each P atom is linked with 3 other P atoms by 3 sigma bond.But, due to smaller atomic size N forms 1 sigma and 2 pi bonds i.e. triple bonds with other N atom and exists as diatomuc molecule.

Answer 2

I don't know the basic reason, but, 2 nitrogen atoms form di-nitrogen atom by triple bonding.

While in case of phosphorus, 1 P atom is linked to 3 other P atoms by a single bond.