The first member of the ketone family is acetone or propanone. Molecular formula is C3H6O or CH3-CO-CH3 or (CH3)2CO. IUPAC Name is Propan-2-one. The common name for ketones is determined by naming the alkyl groups attached to the carbonyl (in alphabetical order), then adding ‘ketone’. Many ketones are of great importance in industry and in biology.