Formulae, functional groups and nomenclature

What the syllabus expects you to be able to do in this topic, in plain English. Match the command word (Describe, Explain, State, etc.) in your answer to score full marks. For the exact wording, see the official syllabus (PDF).

1. Draw Draw a displayed formula that shows every atom and every bond in a molecule, and interpret one.
2. Write Write and interpret the general formulae of homologous series, only for: alkanes, CₙH₂ₙ₊₂; alkenes, CₙH₂ₙ; alcohols, CₙH₂ₙ₊₁OH; and carboxylic acids, CₙH₂ₙ₊₁COOH.
3. Identify Identify a functional group as the part of a molecule, one atom or several, that gives a homologous series its chemical properties.
4. State State that a molecule's structural formula sets out the arrangement of its atoms unambiguously, for example CH₂=CH₂, CH₃CH₂OH and CH₃COOCH₃. Supplement
5. Define Define structural isomers as compounds that share a molecular formula but have different structural formulae, for example the isomers of C₄H₁₀, CH₃CH₂CH₂CH₃ and CH₃CH(CH₃)CH₃, and the isomers of C₄H₈, CH₃CH₂CH=CH₂ and CH₃CH=CHCH₃. Supplement
6. State State that compounds in a homologous series make up a family: they are alike, and their chemical properties are similar because every member contains the same functional group.
7. State State that in a saturated compound, every bond between two carbon atoms in the molecule is a single bond.
8. State State that the molecules of an unsaturated compound contain at least one carbon-carbon bond that is not a single bond.
9. Describe Describe the general features shared by members of a homologous series: one functional group common to all; one general formula; each member differs from the next by a -CH₂- unit; physical properties show a trend; and chemical properties are similar. Supplement