What organic chemistry studies
Organic chemistry studies carbon compounds, especially those built from carbon-hydrogen frameworks and functional groups. Carbon is tetravalent and forms strong C-C bonds, chains, branches and rings. Organic does not mean safe, natural or living: origin and hazard are separate questions.
Butlerov's structural theory
- Atoms in a molecule are connected in a definite order according to their valencies.
- Properties depend on composition and chemical structure.
- Atoms and groups in a molecule mutually influence reactivity.
- A proposed structure can be tested through predicted chemical behavior and experimental evidence.
Carbon valency and skeletons
Neutral carbon normally forms four covalent bonds. A carbon skeleton may be straight, branched or cyclic. Hydrogen completes remaining valencies; a functional group such as -OH, C=C or -COOH creates a characteristic reactive region.
| Representation | Information | Limitation |
|---|---|---|
| Molecular formula | Number of each atom type | Does not show connectivity |
| Displayed formula | Atoms and individual bonds | Can become large |
| Condensed formula | Connectivity in compact form | Needs careful reading |
| Skeletal formula | Carbon framework and functional groups | Carbon-bound H atoms are implicit |
Structure, properties and evidence
Ethanol and dimethyl ether share C2H6O but have different connectivity. Ethanol molecules hydrogen-bond to one another and boil much higher; dimethyl ether has no O-H bond and no self hydrogen bonding. Observed reactions can support a structure, but one test rarely proves it uniquely. Modern structure determination combines chemical evidence with physical measurements.