Introduction to hybridization

The term hybrid refers to the mixing of two or more species. When used in day-to-day life, talk of hybrids would usually conjure up images of bizarre creatures produced through the genetic mixing of two different species. Hybridization in terms of chemistry, however refers to the mixing of atomic orbitals to produce an equivalent number of hybrid orbitals. These hybrid orbitals are energetically more favourable for bonding purposes.

Hybridization theory can be applied to molecules that are more complicated than the simple H₂ molecule. For example, methane (CH₄) is tetrahedral in shape, however when we look at the electronic ground state of carbon, 1s² 2s² 2p_x¹ 2p_y¹ 2p_z⁰, we can see that there are only two unpaired p-electrons. This would imply that carbon has a valency of just two, making it impossible for it to bond with four hydrogens.

So how does carbon form tetrahedral structures?