Title: negative ion
Long Title: IUPAC Gold Book - negative ion
DOI: 10.1351/goldbook.N04098
Status: current

Definition
An atom, radical, molecule or molecular moiety in the vapour phase which has gained one or more electrons thereby acquiring an electrically negative charge. The use of the term anion as an alternative is not recommended because of its connotations in solution chemistry.

Related Terms
- anion: https://goldbook.iupac.org/terms/view/A00358
- moiety: https://goldbook.iupac.org/terms/view/M03968
- positive ion: https://goldbook.iupac.org/terms/view/P04768

Sources
- Orange Book, 2nd ed., p. 204 (https://media.iupac.org/publications/analytical_compendium/)
- PAC, 1991, 63, 1541. 'Recommendations for nomenclature and symbolism for mass spectroscopy (including an appendix of terms used in vacuum technology). (Recommendations 1991)' on page 1549 (https://doi.org/10.1351/pac199163101541)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/N04098/html
- json: https://goldbook.iupac.org/terms/view/N04098/json
- xml: https://goldbook.iupac.org/terms/view/N04098/xml

Citation: Citation: 'negative ion' 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.N04098
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Accessed: 2026-06-24T19:17:17+00:00