Why does the reactivity of nitrogen differ from phosphorus?

Explanation

Nitrogen exists as a diatomic molecule (N = N). Due to the presence of a triple bond between the two N-atoms, the bond dissociationn energy is large (941.4 kJ `mol^(-1)`). As a result, nitrogen is inert and unreactive in its elemental state.
In contrast, white or yellow phosphorus exist as a tetra-atomic molecule `(P_(4))`. Since the P-P single bond is much weaker (213 kJ `mol^(-1)`) than N = N triple bond (941.4 kJ `mol^(-1)`), therefore, phosphorus is much more reactive than nitrogen.