Functional Group: A specific grouping of elements within molecules that are responsible for the characteristic chemical reactions of those molecules.
Aldehyde: An organic compound containing a formyl group (-CHO), which consists of a carbon atom double-bonded to an oxygen atom and single bonded to hydrogen.
Ketone: An organic compound characterized by the presence of a carbonyl group in which the carbon atom is covalently bonded to an oxygen atom and two other atoms or groups.