1. Methane is formed by sp3 hybridisation. In CH4 molecule, the central carbon atom is bounded to four hydrogen atoms.
2. The ground state valence shell electronic configuration of carbon is [He] 2s22px22py12px0
3. In order to form four covalent bonds with the four hydrogen atoms, one of the paired electrons in 2s orbital of carbon is promoted to its 2Pz orbital in the excited state.
4. The one 2s orbital and three 2p orbitals of carbon atom mixes to give four equivalent sp3 hybridised orbitals. The angle between any of the two sp3 hybridised orbitals is 109°•28’
5. The Is orbital of the four hydrogen atoms overlap linearly with the four sp3 hybridised orbitals of carbon to form four C – H σ bonds in the methane molecule as follows