CH301H - Principles of Chemistry I: Honors
Fall 2011, Unique 51040

Lecture Summary, 20 October 2011

Homonuclear Diatomcs:  Today we spent a lot of time constructing MO diagrams of homonuclear diatomic molecules in period 1 and period 2.  We discussed the general rules of LCAO-MO:

  1) Determine the ground state electron configuration of each atom.
  2) AO's interact only if their energy and shape is similar.
  3) Construct MO's from the AO's, where the total number of MO's must equal the number of AO's used.
  4) Arrange the MO's in order of lowest to highest energy.
  5) Add all electrons to MO's using Aufbau (Pauli + Hund's rule).
  6) Determine the bond order of the molecule.

You should be confortable constructing the MO's of all period 1 and period 2 homonuclear diatomics.