Functional groups are specific atoms or groups of atoms in a molecule that determine its chemical properties and reactivity. Each type of organic compound is classified by its functional group.
1. Hydroxyl group (-OH)
- Found in alcohols.
- Makes compounds polar and capable of hydrogen bonding.
- Example: Ethanol
2. Carbonyl group (C=O)
- A carbon double-bonded to oxygen.
- Two main types:
- Aldehydes – carbonyl at the end of the chain
- Ketones – carbonyl in the middle of the chain
- Example: Formaldehyde (aldehyde), Acetone (ketone)
3. Carboxyl group (-COOH)
- Found in carboxylic acids.
- Makes compounds acidic.
- Example: Acetic acid
4. Amino group (-NH2)
- Found in amines and amino acids.
- Acts as a base and can accept protons.
- Example: Methylamine
5. Sulfhydryl group (-SH)
- Found in thiols.
- Can form disulfide bonds, important in proteins.
- Example: Cysteine
6. Ester group (-COO-)
- Found in esters.
- Formed from reaction of a carboxylic acid and alcohol.
- Example: Ethyl acetate
7. Halide group (-X)
- Carbon bonded to a halogen (F, Cl, Br, I).
- Found in alkyl halides.
- Example: Chloromethane
8. Phosphate group (-PO4)
- Found in organic phosphates like DNA and ATP.
- Plays a role in energy transfer in cells.
In short:
Functional groups are specific groups of atoms that give molecules their unique chemical properties. Recognizing them helps predict how a compound will react.