What is the hybridization of the central atom in CH4, and how is it related to its molecular geometry?

• A. sp2 hybridization; trigonal planar.
• B. sp3 hybridization; tetrahedral geometry with bond angles about 109.5°.
• C. sp hybridization; linear.
• D. d2sp3 hybridization; distorted geometry.

Answer: (B)

The central carbon in CH4 uses sp3 hybridization. This comes from mixing one 2s orbital with the three 2p orbitals to create four equivalent sp3 hybrids. Each sp3 hybrid forms a sigma bond with a hydrogen 1s orbital, giving four C–H bonds. Since there are four regions of electron density and no lone pairs on carbon, the electron-pair geometry is tetrahedral, which fixes the molecular geometry to a tetrahedral shape with bond angles of about 109.5°. The other descriptions would imply fewer regions of electron density or an unusual hybridization that doesn’t match methane’s symmetrical, four-bond structure.