Applying Electron Exchange Symmetry Properties to Better Understand Hund’s Rule

A discussion of the shortcomings of Hund’s rule as presented in many current general chemistry textbooks is given. The ideas are developed through a presentation of concepts that are taught in upper-division courses on the same topic of the electronic structure of polyelectronic atoms. Electron exchange symmetry properties are used to demonstrate the need for producing symmetry-adapted linear combinations of both spin and orbital wavefunctions. The results of this analysis are interpreted using the Pauli exclusion principle. Finally, a modified statement of Hund’s rule is suggested that does not conflict with material covered later in the chemistry curriculum.