Question -
Answer -
Electronic configurationof carbon atom:
6C: 1s2 2s2 2p2
In the excited state, theorbital picture of carbon can be represented as:
Hence, carbon atom undergoes sp3 hybridization in CH4 molecule and takes atetrahedral shape.
For a square planar shape, the hybridizationof the central atom has to be dsp2. However, an atom ofcarbon 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 lessbecause of the repulsion existing between the bond pairs. Hence, VSEPR theoryalso supports a tetrahedral structure for CH4.