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Isomerism

Applied Science: BTEC Level 3 National Extended Diploma, topic 4.3.3

Structural Isomerism

Structural isomers are molecules which have the same molecular formula but a different arrangement of atoms in space.

Chain isomers

Chain isomers

  • Chain isomers are molecules that have the same molecular formula but one is linear and one is branched. For example:
  • Butane is a linear molecule with the molecular formula C4H10.
  • Methylpropane is a branched molecule with the molecular formula C4H10.
Position isomers

Position isomers

  • Position isomers are molecules that have the same molecular formula but have their functional group in different places. For example:
  • Butan-1-ol has a hydroxyl group attached to carbon-1.
  • Butan-2-ol has a hydroxyl group attached to carbon-2.
Functional group isomers

Functional group isomers

  • Functional group isomers are isomers that have had their structures changed so that they have different functional groups. For example:
  • Propanoic acid.
  • Methyl ethanoate.

Test yourself on Isomerism

  • What do position isomers have?

  • Which of the following is NOT a chain isomer of pentane?

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