Step 1: Understand what a functional group is. A functional group is a specific group of atoms within a molecule that is responsible for the characteristic chemical reactions of that molecule.
Step 2: Identify the specific functional group for aldehydes. Aldehydes have a unique structure that includes a carbon atom double-bonded to an oxygen atom and also bonded to a hydrogen atom.
Step 3: Write the structure of the aldehyde functional group. This structure is represented as -CHO, where 'C' is carbon, 'H' is hydrogen, and 'O' is oxygen.
Step 4: Conclude that the functional group of aldehydes is -CHO.
