For the tetrahedral arrangement around the central metal atom, there must be four pairs of electrons. For example in methane (CH.) the electronic configuration of central carbon atom is 1s2 2s2 2p2. The single electrons in each of the hydrogen atoms are localized in its Is orbital. The ground state electronic configuration of carbon is 2s2 2p1 2p; and the excited state electronic configuration of carbon is 2e 214 2p; 2p1. These four singly occupied orbitals of carbon atom share four electrons of four hydrogen atoms and results in four bond pairs of electrons in four new hybridized orbitals. These hybrid orbitals are formed by hybridizing Is orbital with 3p orbitals of carbon atom and are designated as se hybridized orbital.
