Term: functional group
https://doi.org/10.1351/goldbook.F02555

Definition:
Organic compounds are thought of as consisting of a relatively unreactive backbone, for example a chain of sp 3 hybridized carbon atoms, and one or several functional groups. The functional group is an atom, or a group of atoms that has similar chemical properties whenever it occurs in different compounds. It defines the characteristic physical and chemical properties of families of organic compounds.

Related Terms:
1) unreactive (http://doi.org/10.1351/goldbook.U06567).
2) backbone (http://doi.org/10.1351/goldbook.B00574).

Source: PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1116 (https://doi.org/10.1351/pac199466051077)

Citation: 'functional group' 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.F02555

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