What is the reason that atomic orbitals hybridize?

Answer 1

Atomic orbital hybridize so that bonding can take place more efficiently (less energy used). Carbon, for example, has a valence of four, and has a ground state of two s electrons, and two p electrons. By exitation of one of the s electrons to a p orbital, we end up with one s electron, and three p electrons. When these four orbitals coalesce (hybridize), we end up with four bonds consisting of sp³ orbitals. These four orbitals point to the four corners of a tetrahedron. Often used to demonstrate this effect, four balloons are tied together at a common center; the balloons then orient themselves to point to the four corners of a tetrahedron. This arrangement is more stable than any other.