Part 1 of a series on Molecular Orbital Theory. Here we cover what a representation is, irreducible representations, and Mulliken symbols. We also assign valence orbitals on a central atom of a molecule to irreducible representations. The mesh orbitals for H2 and H were found using Gaussian16. B3LYP/6-311++G** Picture of Mulliken in 1929 is from Wikipedia. GFHund, CC BY 3.0 , via Wikimedia Commons. :Hund, Character tables by the Gelessus group in Bremen Germany with lots of helpful tools: For practice assigning point groups, this is an excellent website. For more on the art of Matt Bohan, who produces these videos, see Coming in 2025 is a new text Inorganic Chemistry: an Integrated Approach from Oxford Press, which has more on this topic.