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Related to functional group: Homologous series
functional group,in organic chemistry, group of atoms within a molecule that is responsible for certain properties of the molecule and reactions in which it takes part. Organic compounds are frequently classified according to the functional group or groups they contain. For example, methanol, ethanol, and isopropanol are all classified as alcohols since each contains a functional hydroxyl group.
functional group[¦fəŋk·shən·əl ′grüp]
An atom or group of atoms, acting as a unit, that has replaced a hydrogen atom in a hydrocarbon molecule and whose presence imparts characteristic properties to this molecule; frequently represented as R‒. Also known as functionality.