Question

Why does sp mixing arise? How can we use sp mixing to derive more accurate MOs?

Answer 1

ANSWER: s-p mixing occurs when the s and p orbitals have similar energies. When a single p orbital contains a pair of electrons, the act of pairing the electrons raises the energy of the orbital. Thus the 2p orbitals for O, F, and Ne are higher in energy than the 2p orbitals for Li, Be, B, C, and N.