- functional group
a group of atoms responsible for the characteristic behavior of the class of compounds in which the group occurs, as the hydroxyl group in alcohols.[1935-40]
* * *In molecules, any of numerous combinations of atoms that undergo characteristic chemical reactions themselves and in many cases influence the reactivity of the rest of the molecule.Organic compounds are often classified according to the functional groups they contain. Common functional groups include hydroxyl (―OH), in alcohols and phenols; carboxyl (―COOH), in carboxylic acids; carbonyl (―C=O), in aldehydes, ketones, amides, carboxylic acids, esters, and quinones; and nitro (―NO2) and amino (―NH2), in certain organic nitrogen compounds.
* * *any of numerous combinations of atoms that form parts of chemical molecules, that undergo characteristic reactions themselves, and that in many cases influence the reactivity of the remainder of the molecule. In organic chemistry the concept of functional groups is useful as a basis for classification of large numbers of compounds according to their reactions.Some of the common functional groups are hydroxyl, present in alcohols and phenols; carboxyl, present in carboxylic acids; carbonyl, present in aldehydes, ketones, and quinones; and nitro, present in certain organic nitrogen compounds.
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