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 neutralisationThe process of electrolysis, and molten ionic compoundsUsing electrolysis to extract metalsElectrolysis of aqueous solutions
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
Energy Changes
Exothermic and endothermic reactions
- 3 things to know
- Chemistry Paper 1
Overview
Conservation of energy in reactions, exothermic reactions that transfer energy to the surroundings and raise their temperature, examples such as combustion, oxidation and neutralisation, self-heating cans and hand warmers, and endothermic reactions that take in energy and lower the temperature of the surroundings.
What you need to know
Answer each one before you reveal it.
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Key term
A reaction transfers 200 kJ of energy to the surroundings. By how much has the energy stored in the chemicals fallen?
Key term
A student mixes two solutions in a beaker and the beaker becomes warm. What type of energy change has taken place?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What happens to the total amount of energy in the universe during a chemical reaction?
Model answer
It stays exactly the same, because energy is conserved in chemical reactions.
- 2
If a reaction transfers energy to its surroundings, how does the energy stored in the products compare with the energy stored in the reactants?
Model answer
The product molecules store less energy than the reactants, by exactly the amount of energy transferred out.
- 3
A reaction transfers 200 kJ of energy to the surroundings. By how much has the energy stored in the chemicals fallen?
Model answer
By 200 kJ, because the energy gained by the surroundings is exactly the energy the chemicals have lost.
- 4
Define an exothermic reaction.
Model answer
It is a reaction that transfers energy to the surroundings.
- 5
What happens to the temperature of the surroundings during an exothermic reaction?
Model answer
It increases.
- 6
A student mixes two solutions in a beaker and the beaker becomes warm. What type of energy change has taken place?
Model answer
An exothermic change, because energy has been transferred from the reaction to the surroundings.
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