How did quantum mechanics help Linus Pauling explain chemical bonds?

Linus Pauling utilized quantum mechanics as a theoretical framework to explain the nature of chemical bonds and molecular structure. Building upon the work of Walter Heitler and Fritz London, Pauling developed the valence-bond method to describe how atoms interact.12

Key ways he applied quantum mechanics include:

• Valence-Bond Theory: Pauling proposed that a molecule could be described by constructing a wave function representing a paired-electron bond between atoms.21
• Resonance: He introduced the concept of resonance, where a molecule is described as a composite state—a hybrid combination of multiple possible structures—rather than existing in a single, static arrangement. This was instrumental in his analysis of aromatic molecules like benzene.21
• Bond Geometry: He used quantum mechanics to explain the spatial directionality of bonds, such as the tetrahedral structure of the carbon atom, by determining the equivalent strength of the surrounding bonds.21

These contributions were comprehensively detailed in his seminal work, The Nature of the Chemical Bond (1939).21