Please explain hybridisation in NH3.
sp3 hyrbidisation of N atom
Ground state N (Z=7) = 1s2 2s2 2px1 2py2 2pz1
During chemical combination mixing and recasting of 2s, 2px, 2py , 2pz orbitals of nitrogen atom takes place to give four sp3 hybrid orbitals of equivalent energy which are tetrahedrally oriented in space.
In the hybridized state, nitrogen has electronic configuration
1s22(sp3)2 2(sp3)1 2(sp3)1 2(sp3)1
Orbital Overlap
Out of the four sp3 hybrid orbitals, one contains a lone pair of electrons and others are half filled.
Three half filled sp3 hybrid orbitals of N atom overlap axially with half filled 1s orbitals of three hydrogen atoms to form three N-H (sp3-s) sigma covalent bonds.
In ammonia molecule there are three bonding pairs of electrons and one lone pair of electrons.
The forces of repulsion decrease between one pair and bond pair of electrons decrease in the following order
Lone pair-bond pair > Bond pair-bond pair
As a result of this, the bonding pair of electrons are pushed closer and the H-N-H bind angle is reduced from 1090 28’ to 1070 18’
