Recall how boiling point changes with increasing molecular size.

In the subtopic Properties and combustion of hydrocarbons, this learning objective focuses on recall how boiling point changes with increasing molecular size. It sits within Carbon compounds as fuels and feedstock 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 boiling point. Boiling point. means the temperature at which a liquid turns into vapor, which increases with the size of hydrocarbon molecules Avoid the mistake of students think larger hydrocarbons have lower boiling points because they are lighter; instead, explain that larger hydrocarbons have higher boiling points due to increased London dispersion forces, which grow with molecular size and surface area For exam answers, draw a simple table listing a few alkanes (e.g. methane, ethane, propane, butane) with their molecular weights and boiling points. When you see a new alkane, compare its size to the chart to predict whether its boiling point will be higher or lower 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.