Coding for branched chains
3 marks · NormalExplain how to identify a methyl side chain in the structural formula of an organic molecule. Your answer should refer to the features of methyl groups and how to recognize them.
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Must show: mention one-carbon, reference to branching, formula
Common mistakes: confusing methyl with methylene; incorrectly identifying as main chain
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Marking points
M1 · 1 mark · States that a methyl side chain is a group with one carbon atom.
M1 · 1 mark · Mentions that it appears as a branch away from the main chain.
A1 · 1 mark · Correctly writes or describes the structural formula as ().
Worked solution
A methyl side chain consists of a group with one carbon atom () attached to the main carbon chain. It can be identified as a branch extending from the main skeleton, usually written as 'CH3–' or '–CH3'. In structural formulae, it is a 'branch' attached to a carbon atom not forming part of the main chain.