State the general formula for the homologous series of alkenes as CnH2n.

In the subtopic Structure and formulae of alkenes, this learning objective focuses on state the general formula for the homologous series of alkenes as CnH2n. It sits within Reactions of alkenes and alcohols (chemistry only) for AQA GCSE Chemistry 8462 Unit 4.7 Organic chemistry, so the explanation must stay anchored to organic chemistry rather than becoming a generic carbon-compounds fact. Approved keywords to use include alkene, homologous series. Alkene. means a hydrocarbon that contains a carbon-carbon double bond Avoid the mistake of students often state the general formula for alkenes incorrectly as CnH2n+2 instead of CnH2n; instead, remember that alkenes are unsaturated hydrocarbons with a double bond, which means they have two fewer hydrogen atoms than alkanes, leading to the correct formula CnH2n For exam answers, memorize the general formula for alkenes, CnH2n, to quickly identify their structure during the exam Keep molecular formula, structural formula, displayed formula, and general formula distinct. Do not confuse alkanes with alkenes, saturated with unsaturated, cracking with combustion, polymers with monomers, or hydrocarbons with oxygen-containing alcohols and carboxylic acids. When formulae are used, preserve the stored notation exactly and explain the GCSE chemistry idea in words rather than using unsupported displayed-formula diagrams.