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
Quantitative Chemistry
Mass changes when a gas is involved, and measurement uncertainty
- 3 things to know
- Chemistry Paper 1
Overview
Why a metal gains mass when heated in air and a carbonate loses mass when decomposed, apparent breaches of conservation of mass explained with particles, the effect of sealing the container, uncertainty from the range of repeats, accuracy, precision, repeatability and reproducibility, random and systematic errors, anomalous results, resolution and reading scales, and mean, median and mode.
What you need to know
Answer each one before you reveal it.
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Key term
Explain why the mass of solid increases when a metal is heated in an open crucible in air.
Key term
Explain why the mass of solid falls when a metal carbonate is thermally decomposed in an open container.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Explain why the mass of solid increases when a metal is heated in an open crucible in air.
Model answer
Oxygen from the air combines with the metal, so the oxide formed has the mass of the metal plus the mass of the oxygen added to it.
- 2
Explain why the mass of solid falls when a metal carbonate is thermally decomposed in an open container.
Model answer
Carbon dioxide is produced and escapes into the atmosphere, leaving the metal oxide as the only solid product.
- 3
Name the gas that escapes when calcium carbonate is heated strongly.
Model answer
Carbon dioxide.
- 4
Name the solid product left behind when copper carbonate is thermally decomposed.
Model answer
Copper oxide.
- 5
A student says the law of conservation of mass is broken because magnesium gains mass when it burns. Is the student right?
Model answer
No, because the oxygen taken from the air has mass, and once that is counted the total mass is unchanged.
- 6
24 g of magnesium is burned in air and 40 g of magnesium oxide is formed. Explain the increase in terms of particles.
Model answer
Oxygen particles from the air have bonded to the magnesium atoms, so 16 g of oxygen has been added to the solid on the balance.
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