Answer:
A functional group is a group of atoms bonded together in a specific way that can replace a hydrogen atom in a hydrocarbon. In the field of chemistry, a functional group can be described as a atom or group of atoms within a compound which is responsible for given the compound its characteristics.
The molecule shown here contains four functional groups (−OH, −SH, −NH2, and −OPO2−3) attached to a carbon chain that is six carbon atoms long.