Organic Chemistry is a core part of A-Level Chemistry. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
Homologous seriesA family of compounds with the same functional group and general formula.
Functional groupThe reactive part of a molecule that determines its reactions.
IsomerismMolecules with the same formula but different structures or arrangements.
Reaction mechanismStep-by-step electron movement showing how a reaction proceeds.
Alkanes & alkenesSaturated and unsaturated hydrocarbons.
AlcoholsOrganic compounds containing the -OH group.
AlkaneC-C single bonds; CnH(2n+2).
AlkeneContains C=C; CnH2n.
HaloalkaneHalogen replaces H; R-X.
AlcoholContains -OH; R-OH.
Carboxylic acidContains -COOH; weak acid.
EsterContains -COO-R'; formed from acid + alcohol.
Primary alcoholR-CH2OH; oxidises to aldehyde then acid.
Secondary alcoholR2CHOH; oxidises to ketone.
Common mistakes to avoid
Questions where students often pick the tempting wrong answer — make sure you know the right one:
How do alkenes typically react with bromine?✗ Bromine substitutes for a hydrogen on the alkene, releasing HBr. ✓ By electrophilic addition — bromine adds across the double bond to form a dibromoalkane.
What is the product of mild oxidation of a primary alcohol?✗ A primary alcohol is oxidised directly to a ketone. ✓ An aldehyde (which can be further oxidised to a carboxylic acid).
Members of a homologous series share:✗ The same molecular mass ✓ The same functional group and general formula
What is reduction in terms of electrons?✗ Reduction means losing oxygen and oxidation means gaining oxygen — full stop. ✓ Gain of electrons (the oxidation number is reduced).
Why do tertiary halogenoalkanes typically react via SN1 rather than SN2?✗ Tertiary halogenoalkanes react via SN1 because they are more reactive in every way. ✓ The tertiary carbocation intermediate is stabilised by three alkyl groups (positive inductive effect), making the SN1 pathway favourable.
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