08878 IUPAC Gold Book - valence bond theory 10.1351/goldbook.08878 08878 current synonym: VB theory 1 Quantum mechanics theory of chemical bonding that treats electrons as being assigned to individual bonds between particular atoms. The VB theory views a chemical bond as a result of weak coupling (overlapping) of atomic or hybridized atomic orbitals or of both and describes delocalization of electrons (inherent in molecular orbital theory) as a result of resonance mixing of two or more possible energetically equivalent or nearly equivalent structures. VB theory and molecular orbital theory are closely related methods that become equivalent when extended enough. Increasing mixing of VB orbitals gives in the limit extended molecular orbitals. delocalization of electrons https://goldbook.iupac.org//terms/view/08789 molecular orbital theory https://goldbook.iupac.org//terms/view/08841 PAC, 2022, 94, 15. 'Glossary of terms relating to electronic, photonic and magnetic properties of polymers (IUPAC Recommendations 2021)' on page 50 (https://doi.org/10.1515/pac-2020-0501) https://goldbook.iupac.org/terms/view/08878/html https://goldbook.iupac.org/terms/view/08878/json https://goldbook.iupac.org/terms/view/08878/plain Citation: 'valence bond theory' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.08878 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-08-02T22:37:43+00:00