Electronic configuration of carbon atom:
6C:1s2 2s2 2p2
In the excited state, the orbital picture of carbon can be represented as:
Hence, carbon atom undergoes sp3 hybridization in CH4 molecule and takes a tetrahedral
For a square planar shape, the hybridization of the central atom has to be dsp2 . However, an atom of carbon does not have d-orbitalsto undergo dsp2 hybridization. Hence, the structure of CH4 cannot be square planar. Moreover, with a bond angle of 90° in square planar, the stability of CH4 will be very less because of the repulsion existing between the bond pairs. Hence, VSEPR theory also supports a tetrahedral structure for CH4.