9.26C - Drawing and naming the first four alcohols

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.

AlcoholFormula showing OHMolecular formulaCondensed structure
MethanolCH3OHCH4OCH3OH
EthanolC2H5OHC2H6OCH3CH2OH
Propan-1-olC3H7OHC3H8OCH3CH2CH2OH
Butan-1-olC4H9OHC4H10OCH3CH2CH2CH2OH

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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