GCSE Chemistry topics
Find a topic, read the worked example and have a go at the questions. You can select your board and tier when you open an activity.
Studying for AQA or Edexcel? The board pages take you straight into the right question set.
Atoms, formulae and bonding
Start with atoms and ions, then work through formulae and structure.
Periodic table and group trendsUse electronic structure and patterns in Groups 1, 7 and 0 to predict properties.Atoms and ionsFind proton, neutron and electron numbers from atomic number, mass number and ion charge.Writing ionic formulaeCombine positive and negative ions in the ratio needed to make a neutral compound.Relative formula massAdd relative atomic masses, taking care with subscripts and brackets.Bonding, structure and propertiesExplain melting point and electrical conductivity using bonds, particles and mobile charges.
Equations and calculations
Balancing, masses, formulae, solutions and titrations.
Balancing equationsUse whole-number coefficients to balance equations without changing the chemical formulae.Reacting massesUse a balanced equation to calculate a mass of reactant or product.Mass from concentrationConvert solution volume when needed, then calculate the mass of solute.Limiting reactantsFind which reactant runs out first. Higher-tier questions also calculate the maximum mass of product.Percentage yield and atom economyCalculate percentage yield from actual and theoretical masses, then work out atom economy.Percentage composition and formulaeCalculate mass percentages and oxygen gained. Edexcel questions also use empirical and molecular formulae.Formulae from percentagesFor Edexcel: calculate formulae from percentages and explain mass conservation in precipitation reactions.Titration readings and calculationsRead burettes and choose concordant titres. Higher-tier questions also calculate concentration.
Reactions and electrolysis
Predict products and explain which substances react.
Halogen displacement reactionsPredict halogen reactions, compare coloured solutions with controls and infer the reactivity order.Reactions of acidsPredict the salts and other products when acids react with metals, oxides, hydroxides and carbonates.Metal displacement reactionsUse the reactivity series to predict displacement reactions. Higher-tier questions include electron transfer.Electrolysis: electrolytes and electrodesUse the electrolyte, its physical state and the electrode materials to predict the products.Products of electrolysisPredict the products at each electrode. Higher-tier questions also use half-equations.
Rates, energy and equilibrium
Interpret graphs, calculate energy changes and explain equilibrium.
Rates and graphsPlot gas volume against time and calculate mean rate from a table or graph.Rates of reaction: graphsPlot gas-volume data, calculate mean rates and interpret gradients, including tangents where required.Rate investigationsInterpret gas collection and disappearing-cross experiments for AQA and Edexcel.Energy profile diagramsRead energy changes and activation energies from reaction profiles, including the effect of a catalyst.Bond energy calculationsUse bond energies to estimate the energy change for a reaction. Higher tier.Temperature and equilibriumPredict how a temperature change affects equilibrium from the stated energy change. Higher tier.The Haber processRecall how ammonia is made. Higher-tier questions ask you to compare reaction rate and yield.
Organic chemistry
Combustion, cracking and addition reactions of alkenes.
Combustion equationsBalance complete combustion equations and predict the products when oxygen is limited.Cracking hydrocarbonsBalance cracking equations and explain why the shorter hydrocarbons are useful.Addition reactions of alkenesWork out what adds across a C=C bond. The reactions follow your chosen exam board.
Tests and practical work
Identify gases, test unknown salts and interpret chromatograms.
Tests for gasesUse test observations to identify hydrogen, oxygen, carbon dioxide and chlorine.Ion tests and unknown saltsChoose reagents, record test results and identify the ions in an unknown soluble salt.Chromatography and ink separationCalculate Rf values and decide what a chromatogram can tell you about a mixture.
Materials and resources
Corrosion, rust prevention and treating water for drinking.