Why does the reactivity of nitrogen differ from phosphorus ?

Explanation

Nitrogen gas exists as diatomic molecule. Dut to the presence of triple bond between Base N - Atoms bond dissociation energy is high (941.4 KJ / mol). Hence nitrogen is inert and unreactive.
Phosphorus is a tetra atomic molecule and P-P single bond is weaker than `N-=N.P-P` bond dissociation energy is 213 KJ/mole. Hence phosphorus is more reactive than Nitrogen.