Key term
OCR GCSE Combined Science Chemistry J250
Chemical Reactions
Topic overviewWriting formulae of elements and compoundsBalanced equations, and deducing formulae from ionsIonic equations, and state symbolsThe mole and the Avogadro constantConservation of mass, and changes of mass in open systemsStoichiometry, and calculating reacting massesExothermic and endothermic reactions, and reaction profilesActivation energy, and bond energy calculationsOxidation and reduction, by oxygen and by electronsAcids, alkalis and neutralisationThe ionic equation for neutralisation, and reactions of acidsDilute and concentrated, weak and strongThe pH scale, and hydrogen ion concentrationpH as a factor of ten, and measuring pHProducts at the electrodes, and molten ionic compoundsElectrolysis of aqueous solutionsInert and non-inert electrodes
Elements, Compounds and Mixtures
Topic overviewPurity, and melting point dataRelative formula mass and empirical formulaeFormulations, and separating mixturesPaper and thin layer chromatographyInterpreting chromatograms and Rf valuesChoosing a purification methodMetals and non-metals in the Periodic TableElectron arrangement and position in the Periodic TableIonic, covalent and metallic bonding comparedDot and cross diagrams, and the limits of modelsReactions, electron arrangement and Mendeleev's tableCarbon's four bonds, and the variety of organic compoundsDiamond, graphite, fullerenes and grapheneBond strength, intermolecular forces and predicting stateBulk properties of ionic, molecular and giant structures
Global Challenges
Topic overviewExtracting metals by reduction and by electrolysisBiological methods of metal extractionLife cycle assessmentRecycling, and the decisions behind itFractional distillation of crude oilThe fractions, and crude oil as a feedstockDependence on hydrocarbons, and crackingThe Earth's early atmosphere, and how oxygen developedThe greenhouse effect, and evidence for climate changeEffects of carbon dioxide and methane, and air pollutantsProducing potable water
Monitoring and Controlling Chemical Reactions
Topic overviewMass of solute, concentration and dilution calculationsMeasuring the rate of a reaction, and rate graphsFactors affecting rate, and collision theorySurface area and rateCatalysts and how they workReversible reactions and dynamic equilibriumChanging the conditions of an equilibriumActivation energy, and enzymes as catalysts
Particles
Elements, Compounds and Mixtures
Metals and non-metals in the Periodic Table
- 3 things to know
- Paper 9 (Chemistry)
Overview
The typical physical properties of metals and non-metals, the ions each forms and why, metal oxides as basic and non-metal oxides as acidic, graphite as a non-metal that conducts, where metals and non-metals sit in the Periodic Table, why metallic character increases down a group, the elements beside the stepped line, and predicting ion charges from outer electrons.
What you need to know
Answer each one before you reveal it.
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Key term
Give four physical properties typical of non-metals.
Key term
What is produced when a metal burns in oxygen?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Give four physical properties typical of metals.
Model answer
Metals are shiny when freshly cut, good conductors of heat and electricity, malleable and ductile, and usually have high melting points and high densities.
- 2
Give four physical properties typical of non-metals.
Model answer
Non-metals are dull, poor conductors of heat and electricity, brittle when solid, and usually have low melting points and low densities.
- 3
What type of ion does a metal atom form, and why?
Model answer
It forms a positive ion, because it loses the electrons from its outer shell.
- 4
What type of ion does a non-metal atom form, and why?
Model answer
It forms a negative ion, because it gains electrons to complete its outer shell.
- 5
What is produced when a metal burns in oxygen?
Model answer
A metal oxide is produced.
- 6
How does a non-metal oxide behave when it dissolves in water?
Model answer
It is acidic and gives a solution with a pH below 7.
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