Carbon is tetravalent because its 2s and 2p atomic orbitals hybridize to form four sp³ hybrid orbitals. Carbon has four valence electrons, so it can form a maximum of four bonds. When a carbon atom's 2s and 2p orbitals hybridize, they form four equivalent sp³ hybrid orbitals. Each sp³ orbital can form a sigma bond, resulting in a tetrahedral geometry.

Carbon's tetravalency, meaning its ability to form four bonds, is explained by the concept of sp3 hybridization. This hybridization involves the mixing of one s orbital and three p orbitals to create four equivalent sp3 hybrid orbitals. This allows the carbon atom to form four single bonds, as seen in methane (CH\(_4\)).