The carbonyl group, C=O, is probably the most important functional group in organic chemistry, being widespread in nature and the key to many an organic synthesis. Aldehydes and ketones, carboxylic acids, amino acids, amides, esters and related condensation polymers all contain a carbonyl group.
Aldehydes and ketones
the nature of the C=O bond, tests to distinguish between them, oxidation reactions, nucleophilic addition reactions (and mechanism details)
Naming carboxylic acids and their derivatives
including esters, amides, acyl chlorides and acid anhydrides
Why are carboxylic acids acidic?
and so much more so than phenols or alcohols?
Making and breaking esters
esterification reactions, acid hydrolysis, alkaline hydrolysis (and reaction mechanisms for the very keen)
The reactions of acyl chlorides and acid anhydrides
nucleophilic acyl substitution reaction mechanism with water, alcohols, ammonia and amines behaving as nucleophiles