Nitrogen is relatively inactive element because bond dissociation energy of its molecule is fairly high.
Bond dissociation energy
A measurement of the strength of a chemical bond A–B is the bond-dissociation energy. It is the standard enthalpy shift that occurs when A–B is homo lytically cleaved into fragments A and B, which are normally radical species.
The bond-dissociation energy is commonly described as the enthalpy change of the homolysis at 0 K, though the enthalpy change at 298 K is also a commonly encountered parameter.