Title: lambda
Long Title: IUPAC Gold Book - lambda
DOI: 10.1351/goldbook.L03418
Status: current

Definition
Signifies, with its superscript, the bonding number, i.e. the sum of the number of skeletal bonds to an atom and the number of hydrogen atoms associated with it in a parent hydride, real or hypothetical. Its usage in names of compounds is generally restricted to non-standard valence states.

Related Terms
- bonding number: https://dev.goldbook.iupac.org/terms/view/B00703
- parent hydride: https://dev.goldbook.iupac.org/terms/view/P04405
- valence: https://dev.goldbook.iupac.org/terms/view/V06588

Source
- PAC, 1984, 56, 769. 'Treatment of variable valence in organic nomenclature (lambda convention) (Recommendations 1983)' on page 774 (https://doi.org/10.1351/pac198456060769)

Related References
- Blue Book, p. 465 (https://www.acdlabs.com/iupac/nomenclature/)
- Red Book, 3rd ed., p. 245 (https://doi.org/10.1515/pac-2014-0718)

Other Outputs
- html: https://dev.goldbook.iupac.org/terms/view/L03418/html
- json: https://dev.goldbook.iupac.org/terms/view/L03418/json
- xml: https://dev.goldbook.iupac.org/terms/view/L03418/xml

Citation: Citation: 'lambda' 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.L03418
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Accessed: 2026-02-15T11:41:22+00:00