Here are the list of some common functional groups
Alkane : CH3CH2CH3 (propane)
Alkene : CH3CH=CH2 (propene)
Alkyne : CH3C≡CH (propyne)
Alkyl halide : CH3Br (methyl bromide)
Alcohol : CH3CH2OH (ethanol)
Ether : CH3OCH3 (dimethyl ether)
Amine : CH3NH2 (methyl amine)
Aldehyde : CH3CHO (acetaldehyde)
Ketone : CH3COCH3 (acetone)
Acyl chloride : CH3COCl (acetyl chloride)
Carboxylic acid : CH3CO2H (acetic acid)
Ester : CH3CO2CH3 (methyl acetate)
Amide : CH3NH2 (acetamide)
A functional group is defined as an atom or group of atoms within a molecule that has similar chemical properties whenever it appears in various compounds.