Explain the formation of methane using VB theory?

Explanation

(i) Methane is formed by `sp^(3)` hybridisation. In `CH_(4)` molecule, the central carbon atom is bounded to four hydrogen atoms.
(ii) The ground state valence shell electronic configuration of carbon is `[He]2s^(2)" "2p_(x)^(2)" "2p_(y)^(1)" "2p_(z)^(0).`
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 `2p^(z)`, orbital in the excited state.
(iv) The one 2s orbital and three 2p orbitals of carbon atom mixes to give four equivalent `sp^(3)` hybridised orbitals. The angle between any of the two `sp^(3)` hybridised orbitals is `109^(@).28.`

(v) The 1s orbital of the four hydrogen atoms overlap linearly with the four `sp^(3)` hybridised orbitals of carbon to form four `C - H sigma` bonds in the methane molecule as follows: