motnotes - Chemistry Molecular Orbital Theory motnotes Like valence bond theory discussed previously molecular orbital theory is a method of

Chemistry Molecular Orbital Theory motnotes.doc Like valence bond theory discussed previously, molecular orbital theory is a method of mathematically describing the changes in orbitals that take place when bonds occur between atoms. However, unlike valence bond theory which only hybridizes those orbitals that directly take part in end-on ( σ ) bonding, MOT blends all the orbitals in all the energy levels in the bonding atoms. Molecular orbital theory is able to predict some of the observed behavior of molecules that valence bond theory fails to explain. The discussion of MOT will be restricted to those elements of the 1 st and 2 nd period of the periodic table. The best way to understand MOT is to study the diagrams in the chapter and follow the examples but I will outline specific features of this theory that you should pay particular attention to. 1. For each pair of combining atomic orbitals in the original atoms, a new pair of molecular orbitals form to replace them. One orbital (called the bonding molecular orbital) is lower in energy than the original atomic orbitals and contributes to the strength of the bond. The other (known as the