Nitrogen exists as diatomic molecule (N\\\\(\\displaystyle _2\\\\)) with triple bond between two N atoms and phosphorus as P\\\\(\\displaystyle _4\\\\). Nitrogen can form \\\\(\\displaystyle p\\pi-p\\pi\\\\) multiple bonds. Phosphorous cannot form such bonds due to repulsion between non bonded electrons of inner core. In case of nitrogen, there is no such repulsion as it has only 1s electrons in inner shell so that the overlap of p orbitals to form pi bonds is easy.