02899 IUPAC Gold Book - hydrogen bond 10.1351/goldbook.H02899 H02899 current 1 A form of association between an electronegative atom and a hydrogen atom attached to a second, relatively electronegative atom. It is best considered as an electrostatic interaction, heightened by the small size of hydrogen, which permits proximity of the interacting dipoles or charges. Both electronegative atoms are usually (but not necessarily) from the first row of the Periodic Table, i.e. $\ce{N}$, $\ce{O}$ or $\ce{F}$. Hydrogen bonds may be inter-molecular or intramolecular. With a few exceptions, usually involving fluorine, the associated energies are less than \(\pu{20\!-\! 25 kJ mol-1}\) (\(\pu{5\!{-}\! 6 kcal mol-1}\)). association https://goldbook.iupac.org/terms/view/A00472 intramolecular https://goldbook.iupac.org/terms/view/I03130 PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1123 (https://doi.org/10.1351/pac199466051077) https://goldbook.iupac.org/terms/view/H02899/html https://goldbook.iupac.org/terms/view/H02899/json https://goldbook.iupac.org/terms/view/H02899/plain Citation: 'hydrogen bond' 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.H02899 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. 2026-06-29T20:13:32+00:00