Definition of Functional Group
A functional group is a group in which some specific atoms are bonded to each other in such a particular way to give the compound specialized physicochemical properties. Regarding organic chemistry, these functional groups allow the compounds to undergo characteristic chemical reactions. The same functional groups tend to undergo similar chemical reactions irrespective of the compound. Moreover, these functional groups also play an important role in nomenclature.
The combination of the names of the functional groups with the names of the parent alkanes helps us in distinguishing compounds. The carbon atom that is attached to the functional group is termed alpha carbon. The next to it is beta carbon and then gamma carbon etc. In the same manner, the functional group can be regarded as primary, secondary, tertiary depending on its attachment to the carbon atom. Examples include alcohol, ether, ketone, aldehyde, carboxylic acid, etc.