Key term
AQA GCSE Chemistry 8462
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 7Transition metals, and how they differ from Group 1
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 fullerenesSizes of particles and their propertiesUses of nanoparticles
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 neutralisationTitrationsStrong 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
Topic overviewCrude oil, hydrocarbons and alkanesFractional distillation and petrochemicalsProperties of hydrocarbonsCracking, and testing alkenes with bromine waterWhy cracking is useful, and equations for itStructure and formulae of alkenesReactions of alkenesAlcoholsCarboxylic acidsAddition polymerisationCondensation polymerisationAmino acids, DNA and naturally occurring polymers
Quantitative Chemistry
Topic overviewConservation of mass and balanced chemical equationsRelative formula mass and concentration of solutionsMass changes when a gas is involved, and measurement uncertaintyMolesAmounts of substances in equations, and balancing using molesLimiting reactantsPercentage yieldAtom economyUsing concentrations of solutions in mol/dmUse of amount of substance in relation to volumes of gases
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
Using Resources
Topic overviewUsing the Earth's resources and sustainable developmentProducing potable water in the UKDesalination, and analysing water samplesWaste water treatmentAlternative methods of extracting metalsLife cycle assessmentWays of reducing the use of resourcesCorrosion and its preventionAlloys as useful materialsGlass, clay ceramics and polymersComposites, and comparing materialsThe Haber processProduction and uses of NPK fertilisers
Energy Changes
The energy change of reactions
- 3 things to know
- Paper 1
Overview
Breaking bonds as endothermic and making bonds as exothermic, bond energy, calculating the overall energy change from the energy needed to break reactant bonds and the energy released forming product bonds, why the change is negative for exothermic and positive for endothermic reactions, and worked bond energy calculations.
What you need to know
Answer each one before you reveal it.
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Key term
Explain why a reaction can be exothermic overall even though energy has to be supplied to start it.
Key term
What two kinds of change to chemical bonds take place in every chemical reaction?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What two kinds of change to chemical bonds take place in every chemical reaction?
Model answer
Bonds in the reactants are broken and new bonds are made in the products.
- 2
Why must energy be supplied to the reactants at the start of a reaction?
Model answer
Energy is needed to break the bonds in the reactant molecules.
- 3
What happens to energy when new bonds form in the products?
Model answer
Energy is released to the surroundings.
- 4
Is breaking a chemical bond exothermic or endothermic?
Model answer
Endothermic, because energy must be supplied to break it.
- 5
Is forming a chemical bond exothermic or endothermic?
Model answer
Exothermic, because energy is released as the bond forms.
- 6
What is meant by the bond energy of a particular bond?
Model answer
It is the energy needed to break that bond, and the same amount of energy is released when that bond is made.
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