On Teaching Molecular Term Symbols: From the Atomic Term Symbols in a Two-Dimensional World to the Molecular Term Symbols in a Three-Dimensional World

摘要

In the article "A Systematic Method for Determining Molecular Term Symbols for Diatomic Molecules Using Uncoupled-States Orbital Diagrams" in this Journal, Campbell introduced a systematic method to determine the molecular term symbols for diatomic molecules. This method is introduced in various undergraduate Physical Chemistry textbooks because of its practicality. However, there remains one question that may baffle some students: Why is |M-L| = A used when determining the molecular term symbols whereas it is |M-L| = L for atomic term symbols? This letter aims to provide a more comprehensive yet clear answer to this question, which, I hope, will help students better understand molecular term symbols and polish their creative problem-solving skills.