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
Chemical Changes
Representation of reactions at electrodes as half equations
- 3 things to know
- Chemistry Paper 1
Overview
Why cathode reactions are reductions and anode reactions oxidations, half equations for metal ions, hydrogen ions, halide ions, oxide ions and hydroxide ions, balancing atoms and charge, and the two ways of writing an oxidation.
What you need to know
Answer each one before you reveal it.
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Key term
Write the half equation for lead ions being discharged at the cathode.
Key term
Write the half equation for aluminium ions being discharged at the cathode.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Why are the reactions taking place at the cathode described as reductions?
Model answer
The positive ions arriving there gain electrons.
- 2
Write the half equation for lead ions being discharged at the cathode.
Model answer
Pb²⁺ + 2e⁻ → Pb.
- 3
Write the half equation for aluminium ions being discharged at the cathode.
Model answer
Al³⁺ + 3e⁻ → Al.
- 4
Why are the reactions taking place at the anode described as oxidations?
Model answer
The negative ions arriving there lose electrons.
- 5
Write the half equation for chloride ions being discharged at the anode.
Model answer
2Cl⁻ → Cl₂ + 2e⁻.
- 6
Write the half equation for bromide ions being discharged at the anode.
Model answer
2Br⁻ → Br₂ + 2e⁻.
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