Lesson 3 of 13 · 7 min
Classification of organic compounds
NCERT § "Classification of Organic Compounds"
Vinegar, the formic acid in an ant bite and the smell of rancid butter all come from the same family of compounds. Chemists have sorted millions of organic molecules into families like this, first by skeleton, then by the working group they carry.
The lesson in notes
In short
Acyclic or open-chain (aliphatic) compounds have straight or branched chains, such as ethane and acetic acid.
Alicyclic compounds have rings made only of carbon but behave like aliphatic compounds, such as cyclohexane.
Aromatic compounds include benzenoid compounds (benzene and its derivatives) and non-benzenoid compounds such as tropone.
Heterocyclic compounds have one or more non-carbon atoms (N, O or S) in the ring; furan, thiophene and pyridine are examples, and they can be aromatic.
A functional group is the atom or group that gives a family of compounds its characteristic chemical properties, such as –OH, –CHO or –COOH.
A homologous series is a family with the same functional group in which successive members differ by a –CH₂ unit; members show similar chemistry and a gradual change in physical properties.