1.03 | Molecular Point Groups and Orbital Diagrams

June 3rd, 2024. In this third lecture, we have finished the molecular point groups and have gained experience in assigning the point groups by using the flow-chart that is attached in the course materials of this class. Next we learned how to construct the molecular orbital diagrams of simple diatomic molecules (e.g., N2, O2, CO, etc..) and triatomic (e.g., CH2, OH2) by using the method of inspection, taking into account the symmetry and energy of the used molecular orbitals. By using the MO diagrams, we were also able to explain why dioxygen is paramagnetic, and why the two lone-pairs of water are inequivalent. However, we also realized that when the molecules get more complicated, a different approach is necessary for constructing the molecular orbitals diagrams. At the end of the class, we started with a new approach that centered around using Symmetry Adapted Linear Combinations (SALCs) of atomic orbitals, to find the symmetry of the irreducible representations.

The video to today’s lecture can be found below: