9.26C - Drawing and naming the first four alcohols
Learn the formulae of the first four alcohols and how to draw every bond in their molecules. Here, propanol means propan-1-ol and butanol means butan-1-ol, with the OH group on an end carbon.
Names and formulae
The prefixes meth-, eth-, prop- and but- mean one, two, three and four carbon atoms. Each step down the series adds CH2.
| Alcohol | Formula showing OH | Molecular formula | Condensed structure |
|---|---|---|---|
| Methanol | CH3OH | CH4O | CH3OH |
| Ethanol | C2H5OH | C2H6O | CH3CH2OH |
| Propan-1-ol | C3H7OH | C3H8O | CH3CH2CH2OH |
| Butan-1-ol | C4H9OH | C4H10O | CH3CH2CH2CH2OH |
A molecular formula counts all atoms. A condensed structural formula also shows how groups connect. C2H5OH keeps the alcohol's OH group visible; its six hydrogen atoms include the one bonded to oxygen.
Drawing and checking every bond
A displayed structure shows every atom and every covalent bond as a line. Carbon forms four bonds, oxygen two and hydrogen one in these neutral molecules. Oxygen joins a carbon to a hydrogen: C–O–H.
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