HomeLearn Fast select Course
Show Unit/ChapterChange UnitChange SubjectLast Menu
NEET-XI-Chemistry

04: Chemical Bonding and Molecular Structure

 page 2
Qstn# 21 Prvs-QstnNext-Qstn
  • #21
    Apart from tetrahedral geometry, another possible geometry for CH4 is square planar with the four H atoms at the corners of the square and the C atom at its centre. Explain why CH4 is not square planar?
    Ans : 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 shape.



    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.