Covalent Bonding: Orbital Overlap and Hybridization Lecture 7

VSEPR is a simplification and does not explain much. There is one more theory: valence bond (VB)!

Key principle of the Valence Bond Theory: A covalent bond forms when the orbitals of two atoms overlap and the overlap region, which is between the nuclei, is occupied by a pair of electrons. The two wave functions are in phase so the amplitude increases between the nuclei.

A covalent bond forms when the orbitals of two atoms overlap and the overlap region, which is between the nuclei, is occupied by a pair of electrons.

The two wave functions are in phase so the amplitude increases between the nuclei.

Themes of the Valence Bond Theory: A set of overlapping orbitals has a maximum of two electrons that must have opposite spins. The greater the orbital overlap, the stronger (more stable) the bond. The valence atomic orbitals in a molecule are different from those in isolated atoms. There is a hybridization of atomic orbitals to form molecular orbitals.

A set of overlapping orbitals has a maximum of two electrons that must have opposite spins.

The greater the orbital overlap, the stronger (more stable) the bond.

The valence atomic orbitals in a molecule are different from those in isolated atoms.

There is a hybridization of atomic orbitals to form molecular orbitals.

Hybridization is the process of orbital mixing. It result in hybrid orbitals.

Key points about hybridization: The number of hybrid (molecular) orbitals obtained equals the number of of atomic orbitals mixed. The type of hybrid orbitals obtained varies with the types of atomic orbitals mixed.

The number of hybrid (molecular) orbitals obtained equals the number of of atomic orbitals mixed.

The type of hybrid orbitals obtained varies with the types of atomic orbitals mixed.

sp-Hybridization

sp 2 -Hybridization

sp 3 -Hybridization

sp-Hybridization

sp-Hybridization

sp-Hybridization

spd-Hybridization

Formation of  -bond

Formation of  -bond

 - and  - bonds in ethylene

 - and  -bonds

 -(sigma) bond

 -(pi) bond

THE END