Term: isomer
https://doi.org/10.1351/goldbook.I03289

Definition:
One of several species (or molecular entities) that have the same atomic composition (molecular formula) but different line formulae or different stereochemical formulae and hence different physical and/or chemical properties.

Related Terms:
1) molecular entities (http://doi.org/10.1351/goldbook.M03986).
2) line formulae (http://doi.org/10.1351/goldbook.L03561).
3) stereochemical formulae (http://doi.org/10.1351/goldbook.S05974).
4) molecular formula (http://doi.org/10.1351/goldbook.M03987).

Source: PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1129 (https://doi.org/10.1351/pac199466051077)

Citation: 'isomer' 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.I03289

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