Hybridization

*Intermixing of two or more pure atomic orbitals with different characteristics of same atom with almost same energy to give same number of identical and degenerate new type of orbitals is known as hybridization. The new orbitals formed are also known as hybrid orbitals.

E.g.
*If, one 's' and one 'p' orbitals of almost equal energy intermix to give two identical and degenerate hybrid orbitals, called sp hybrid orbitals.

*If, one 's' and two 'p' orbitals of almost equal energy intermix to give three identical and degenerate hybrid orbitals, called sp2 hybrid orbitals.

*If, one 's' and three 'p' orbitals of almost equal energy intermix to give four identical and degenerate hybrid orbitals, called sp3 hybrid orbitals.

  

*Hybridization is suitable for the pairing of electrons to form chemical bonds in valence bond theory.
*Provides a quantum mechanical insight to Lewis structures thus, during this process, the wave functions, Ψ of atomic orbitals of same atom are combined to give new wave functions corresponding to hybrid orbitals.

*The new orbitals have the same total electron capacity as the old ones.

*The properties and energies of the new, hybridized orbitals are an 'average' of the original unhybridized orbitals.

*Hybrid orbitals are very useful in the explanation of molecular geometry and atomic bonding properties. (Although sometimes it taught together with the valence shell electron-pair repulsion (VSEPR) theory but notice that valence bond and hybridization are in fact not related to the VSEPR model.)
*Hybrid orbitals cannot be used to interpret photoelectron spectra.
*Photoelectron spectra measure the energies of ionized states, identified with delocalized orbital energies using Koopmans' theorem (The first ionization energy of a molecular system is equal to the negative of the orbital energy of the highest occupied molecular orbital, HOMO, or for closed-shell systems, the negative of the HOMO energy is the ionization potential i.e. the energy required to form the cation provided that the ionization process is adequately represented by the removal of an electron from an orbital without change in the wave-functions of the other electrons.)
*Structure and hybridization: Click here.