Key term
AQA GCSE Combined Science Chemistry 8464
Atomic Structure and the Periodic Table
Topic overviewAtoms, elements and compoundsWord equations, symbols and balanced equationsMixturesFrom the plum pudding model to the nuclear modelBohr, Chadwick and the modern model of the atomRelative electrical charges of subatomic particlesSize and mass of atomsRelative atomic mass and electronic structureThe periodic tableDevelopment of the periodic tableMetals and non-metalsGroup 0Group 1Group 7
Bonding, Structure, and the Properties of Matter
Topic overviewChemical bonds, including metallic bondingIonic bondingIonic compoundsCovalent bonding and how it is representedThe three states of matter and changes of statePredicting state, state symbols, and the limits of the particle modelProperties of ionic compoundsProperties of small moleculesPolymers and giant covalent structuresProperties of metals and alloys, and why metals conductDiamond and graphiteGraphene and fullerenes
Chemical Analysis
Chemical Changes
Topic overviewThe reactivity seriesMetal oxides, extraction, and redox in terms of electronsAcids reacting with metals, neutralisation and saltsSoluble saltsThe pH scale and neutralisationStrong and weak acidsThe process of electrolysis, and molten ionic compoundsUsing electrolysis to extract metalsElectrolysis of aqueous solutionsRepresentation of reactions at electrodes as half equations
Chemistry of the Atmosphere
Topic overviewThe Earth's early atmosphereHow oxygen increased and carbon dioxide decreasedThe gases in today's atmosphere, and which are greenhouse gasesHuman activities which contribute to an increase in greenhouse gases in the atmosphereGlobal climate change and carbon footprintsAtmospheric pollutants from fuels, and their effects
Energy Changes
Organic Chemistry
Quantitative Chemistry
The Rate and Extent of Chemical Change
Topic overviewMeasuring the mean rate of a reactionRate from graphs, and the gradient of a tangentFactors which affect the rates of chemical reactionsCollision theory and activation energyCatalystsReversible reactions and dynamic equilibriumThe effect of changing conditions on equilibriumThe effect of changing concentrationThe effect of temperature changes on equilibriumThe effect of pressure changes on equilibrium
Organic Chemistry
Properties of hydrocarbons
- 3 things to know
- Chemistry Paper 2
Overview
How boiling point, viscosity and flammability depend on molecular size, what viscosity and flammability mean, complete combustion of hydrocarbons to carbon dioxide and water as an exothermic oxidation, balanced combustion equations for methane, ethane and propane, and choosing hydrocarbons as fuels.
What you need to know
Answer each one before you reveal it.
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Key term
What is meant by the viscosity of a liquid?
Key term
What is meant by the flammability of a fuel?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Name three properties of a hydrocarbon that depend on the size of its molecules.
Model answer
Boiling point, viscosity and flammability.
- 2
What is meant by the viscosity of a liquid?
Model answer
Viscosity is how easily a liquid flows; a liquid of high viscosity is thick and flows slowly.
- 3
What is meant by the flammability of a fuel?
Model answer
Flammability is how easily the fuel catches fire and burns.
- 4
Explain why the size of its molecules decides how a hydrocarbon is used as a fuel.
Model answer
Molecular size controls boiling point, viscosity and flammability, so small molecules make gases and petrol that ignite easily, while large molecules make thick liquids burned in furnaces and ships.
- 5
How does the boiling point of a hydrocarbon change as its molecules get larger?
Model answer
The boiling point increases.
- 6
How does viscosity change as hydrocarbon molecules get larger?
Model answer
Viscosity increases, so the liquid flows less easily.
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