Functional groups and molecular properties

Functional groups are recurring arrangements of atoms that help explain organic molecules' properties and reactions. An alcohol contains a hydroxyl group attached to a saturated carbon. A carboxylic acid contains a carboxyl group, which includes both a carbonyl and a hydroxyl on the same carbon. Ethanol is an alcohol; ethanoic acid is a carboxylic acid. Both contain oxygen, but their different bonding patterns give them different chemical behaviour. The whole molecule still matters: a functional group is a useful clue, not a complete description.