Maximum covalency of nitrogen is four. Explain. 

Explanation

Nitrogen has no valence d-orbitals. Excitation of 2s electron to 3s orbital is difficult. Hence nitrogen does not form five bonds. `N(Z=7):[He] 2s^(2)2p^(1)2p^(1) 2p^(1)`. Nitrogen can form three covalent bonds and one dative bond as in `NH_(4)^(+)` or in `C_(6)H_(5)NH_(3)^(+)` ions. Its maximum covalency is four.