Term: chemical reaction
https://doi.org/10.1351/goldbook.C01033

Definition:
A process that results in the interconversion of chemical species. Chemical reactions may be elementary reactions or stepwise reactions. (It should be noted that this definition includes experimentally observable interconversions of conformers.) Detectable chemical reactions normally involve sets of molecular entities as indicated by this definition, but it is often conceptually convenient to use the term also for changes involving single molecular entities (i.e. 'microscopic chemical events').

Related Terms:
1) identity reaction (http://doi.org/10.1351/goldbook.I02940).
2) chemical species (http://doi.org/10.1351/goldbook.CT01038).
3) elementary reactions (http://doi.org/10.1351/goldbook.E02035).
4) stepwise reactions (http://doi.org/10.1351/goldbook.S05970).
5) molecular entities (http://doi.org/10.1351/goldbook.M03986).

Source: PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1096 (https://doi.org/10.1351/pac199466051077)

Citation: 'chemical reaction' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.C01033

License: 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.

Disclaimer: 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.