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functional group n.
An atom or group of atoms, that replaces hydrogen in an organic compound and that defines the structure of a family of compounds and determines the properties of the family.
|functional group |
An atom or group of atoms that replaces hydrogen in an organic compound. Functional groups define the structure of a family of compounds and determine its properties. The carboxyl and hydroxyl groups are functional groups that define the compounds they are part of as organic acids and alcohols, respectively.