Carboxyl group

Carboxyl group or carboxy group -COOH or CO2H is a functional group present in amino acids and carboxylic acids. Its structure composed of one carbon atom attached to an oxygen atom by double bond and to a hydroxyl group by a single bond. It is often mentioned that a carboxyl group is a carbonyl group bonded to a hydroxyl group. The carboxyl group has one valence electron in its carbon atom, making it possible to be a part in a larger molecule by bonding through it.