Functional Groups

A functional group is an atom or group of atoms responsible for the characteristic chemical reactions of a molecule.Common functional groups at AS include: C=C in alkenes (suffix -ene), -OH in alcohols (-ol), a halogen atom in halogenoalkanes (prefix chloro-, bromo- or iodo-), -CHO in aldehydes (-al), C=O within the chain in ketones (-one) and -COOH in carboxylic acids (-oic acid).Compounds with the same functional group react in similar ways, whatever the length of the carbon chain. For example, ethanol and butan-1-ol both react as alcohols.The rest of the molecule, the hydrocarbon chain, is often written as R. For example, R-OH is a general alcohol and R-COOH a general carboxylic acid.