The nitrogen atom of the amino group is usually sp3 hybridised. As the atomic number of nitrogen is 7 , the valence shell has 5 electrons i.e 2s22p3(1s and 3p orbitals are participating in hybridization). one pair of electron acts as a lone pair and the remaining three electrons forms bonds with either hydrogens or alkyl or aryl groups. Nitrogen also shows sp2 hybridization, where there are only 2 bonds are formed, one among them forming a partial double bond or a double bond.