GCSE Chemistry Exam Study Guide (2027)
Everything the GCSE Chemistry (9-1) Exam tests, topic by topic: what each section covers, the facts that come up most, and how to study it. Pair it with the free 15-question practice test.
The exam at a glance
| Questions | AQA: 2 written papers, 100 marks each (200 marks in total), Foundation or Higher tier |
|---|---|
| Time | 3 hours 30 minutes in total (2 × 1 hour 45 minutes) |
| Grades and pass mark | Grade 4 is a standard pass and grade 5 a strong pass. Boundaries are set after every exam series, so aim for 70% in practice |
| Format | Written exam, calculator allowed, periodic table provided. Foundation tier covers grades 1 to 5 and Higher tier grades 4 to 9 |
| Exam boards | AQA, Pearson Edexcel and OCR |
| Test provider | At your school or college, or as a private candidate at an exam centre that accepts them |
Mind map: the whole exam on one screen
Read the complete GCSE Chemistry study notes for “Atomic Structure and the Periodic Table”
Our first full set of comprehensive notes, about 18 minutes of reading: Atoms, elements and compounds · Inside the atom · Isotopes and relative atomic mass · How the model of the atom developed · Electronic structure and the periodic table · Group 0 and Group 1 · Group 7 and the transition metals, a worked exam example, the traps examiners use and a one-minute recap. Create a free account to read it and see how premium notes work before you decide.
1. Atomic Structure and the Periodic Table
AQA topic 1 (Paper 1, and assumed knowledge for Paper 2): atoms, isotopes, the development of atomic models, electronic structure, how the periodic table is arranged and the trends in Groups 0, 1 and 7 plus the transition metals.
Key facts
- Protons (relative mass 1, charge +1), neutrons (mass 1, charge 0) and electrons (mass very small, charge −1). Atomic number = protons; mass number = protons + neutrons.
- Isotopes are atoms of the same element with different numbers of neutrons. Relative atomic mass is the weighted mean: Ar = Σ(isotope mass × abundance) ÷ 100.
- Atomic models: Dalton's solid spheres, Thomson's plum pudding (electron discovered), Rutherford's nuclear model from alpha scattering, Bohr's electron shells, then Chadwick's neutron (1932).
- Electrons fill shells 2, 8, 8 for the first 20 elements. Group number = outer electrons; period number = number of shells.
- Mendeleev left gaps and sometimes swapped order to keep elements with similar properties together; the discovery of isotopes later explained why ordering by atomic weight did not always work.
- Group 1 (alkali metals) react with water to give a metal hydroxide and hydrogen; reactivity increases down the group. Group 7 (halogens) are diatomic, reactivity decreases down the group, and a more reactive halogen displaces a less reactive one from its salt.
- Group 0 (noble gases) are unreactive because they have full outer shells; boiling points increase down the group.
- Mixtures are separated by filtration, crystallisation, simple and fractional distillation and chromatography. Transition metals (Chemistry only) have higher melting points and densities than Group 1, form coloured compounds, ions with different charges and act as catalysts.
Flashcards
Exam tip: Mark schemes reward 'outer electron' and 'further from the nucleus' or 'more shielding'. Always explain reactivity trends in terms of electrons, never just 'bigger atoms'.
2. Bonding, Structure and Properties
AQA topic 2: ionic, covalent and metallic bonding, the states of matter, and how structure explains melting point, conductivity and hardness. Includes giant covalent carbon, polymers and nanoparticles.
Key facts
- Ionic bonding: metal atoms transfer electrons to non-metal atoms, forming ions with noble-gas structures held by strong electrostatic forces in a giant lattice.
- Ionic compounds have high melting points and conduct electricity when melted or dissolved, because the ions can then move.
- Covalent bonds are shared pairs of electrons. Simple molecules (H₂O, CO₂, CH₄) have low melting points because only weak intermolecular forces are overcome, not the covalent bonds.
- Giant covalent structures (diamond, graphite, silicon dioxide) have very high melting points because many strong covalent bonds must be broken.
- Diamond: each C bonded to 4 others, very hard, does not conduct. Graphite: each C bonded to 3 others in layers with delocalised electrons, so it conducts and is soft. Graphene is a single layer; fullerenes (C₆₀) are hollow cages; nanotubes are cylinders.
- Metallic bonding: positive ions in a sea of delocalised electrons. Metals conduct heat and electricity and are malleable as layers slide. Alloys are harder because different-sized atoms distort the layers.
- State symbols: (s), (l), (g), (aq). The particle model assumes particles are solid spheres with no forces, which is a limitation.
- Nanoparticles are 1 to 100 nm across and have a very high surface area to volume ratio; when the side of a cube falls by a factor of 10, the surface area to volume ratio rises by a factor of 10.
Flashcards
Exam tip: When explaining melting points, always name what is overcome: 'strong electrostatic forces between ions', 'strong covalent bonds' or 'weak intermolecular forces'. Saying 'strong bonds' alone rarely gets the mark.
3. Quantitative Chemistry
AQA topic 3: conservation of mass, relative formula mass, moles (Higher), reacting masses, limiting reactants, concentration, yield, atom economy and gas volumes. The most calculation-heavy topic and tested on both papers.
Key facts
- Mass is conserved in a reaction. An apparent change in mass usually means a gas has left or entered an open container.
- Mr is the sum of the Ar values in the formula. Percentage by mass of an element = (Ar × number of atoms ÷ Mr) × 100.
- One mole contains 6.02 × 10²³ particles (the Avogadro constant). Moles = mass ÷ Mr.
- Reacting masses: find moles of the known substance, use the balancing ratio, then convert back to mass. The limiting reactant is the one that is used up first.
- Concentration (g/dm³) = mass ÷ volume (dm³); (mol/dm³) = moles ÷ volume (dm³). 1 dm³ = 1000 cm³.
- Percentage yield = (actual mass ÷ theoretical mass) × 100. Yields are below 100% because of incomplete reactions, side reactions and losses when separating the product.
- Atom economy = (Mr of desired product ÷ total Mr of all reactants) × 100. High atom economy means less waste.
- At room temperature and pressure one mole of any gas occupies 24 dm³ (Chemistry only). Titrations use a burette and pipette to find an unknown concentration (Chemistry only, Higher for the calculation).
Flashcards
Exam tip: Write the formula you are using before substituting numbers and carry units through. In mole questions, set out three lines: moles of known, ratio, mass of unknown.
Test yourself on these topics
Take the free 15-question GCSE Chemistry test, then save your results to unlock your Readiness Score and the mistakes bank.
4. Chemical Changes and Energy Changes
AQA topics 4 and 5: the reactivity series, extraction of metals, oxidation and reduction, acids, bases and salts, pH, electrolysis, exothermic and endothermic reactions, bond energies, and cells and fuel cells.
Key facts
- Reactivity series (K, Na, Li, Ca, Mg, (C), Zn, Fe, (H), Cu). Metals below carbon are extracted by reduction with carbon; metals above carbon by electrolysis.
- Oxidation is gain of oxygen or loss of electrons; reduction is loss of oxygen or gain of electrons (OIL RIG, Higher). Ionic equations show only the ions that change.
Flashcards
Exam tip: For electrolysis of solutions, decide each electrode separately: cathode (metal or hydrogen?) and anode (halogen or oxygen?). Half equations are Higher only, but the products are tested on both tiers.
5. Rates and Equilibrium
AQA topic 6 (Paper 2): measuring and calculating rates, collision theory, the factors that affect rate, catalysts, reversible reactions and Le Chatelier's principle.
Key facts
- Mean rate = quantity of reactant used or product formed ÷ time. Units are g/s, cm³/s or mol/s (Higher). The gradient of a tangent on a graph gives the rate at a given time (Higher).
- Collision theory: reactions happen when particles collide with at least the activation energy. Rate depends on the frequency of successful collisions.
Flashcards
Exam tip: Collision theory answers need 'more frequent collisions' or 'more collisions per second'. 'More collisions' alone loses the mark.
6. Organic Chemistry and Chemical Analysis
AQA topics 7 and 8 (Paper 2): crude oil, alkanes, fractional distillation, cracking, alkenes, alcohols, carboxylic acids, polymers and natural polymers, plus purity, formulations, chromatography, gas tests and ion tests.
Key facts
- Crude oil is a mixture of hydrocarbons, mostly alkanes (CₙH₂ₙ₊₂). Fractional distillation separates it by boiling point; shorter chains have lower boiling points, are less viscous and more flammable.
- Complete combustion of a hydrocarbon gives carbon dioxide and water. Cracking (catalytic or steam) breaks long alkanes into shorter alkanes and alkenes, which are more useful.
Flashcards
Exam tip: Learn the colours as a table and test yourself both ways round (ion to colour, and colour to ion). They are quick marks that students often mix up under pressure.
7. The Atmosphere and Using Resources
AQA topics 9 and 10 (Paper 2): how the atmosphere evolved, greenhouse gases, climate change, carbon footprints and pollutants, plus potable water, waste water, life cycle assessments, corrosion, alloys, ceramics, composites and the Haber process.
Key facts
- Today's dry air is about 80% nitrogen, 20% oxygen, with small amounts of carbon dioxide, water vapour and noble gases.
- Early atmosphere: mostly carbon dioxide from volcanoes. Oxygen increased through photosynthesis by algae and plants; CO₂ fell as it dissolved in oceans and was locked into sedimentary rocks and fossil fuels.
Flashcards
Exam tip: Six-mark questions on climate change or life cycle assessments need balanced points. Plan two or three linked statements on each side before writing.
How to pass
- 100 marks in 105 minutes is about 1 minute a mark. Use the multiple-choice and 1-mark recall questions to bank time for the 6-mark extended answers.
- Show every step in calculations: write the equation, substitute with units, then give the answer to the significant figures asked for. Method marks are awarded even if the final answer is wrong.
- Paper 2 can also test the fundamentals from topics 1 to 3 (atomic structure, bonding, moles), so keep revising them right up to the second exam.
- Learn the 8 required practicals as method, variables, risks and expected results. AQA says at least 15% of marks test practical skills.
- Read command words carefully: 'describe' means say what happens, 'explain' means give the reason, and 'compare' needs a statement about both things.
Frequently asked questions
How long should I study for the GCSE Chemistry exam?
Most students do best starting 10 to 12 weeks before the first paper, with 30 to 45 minutes a day per subject. You're ready once your Readiness Score has stayed at 80 or higher for about a week.
Can I take the GCSE Chemistry exam online?
No. GCSE Chemistry is a written exam sat in person at your school, college or an approved exam centre. Format: written exam, calculator allowed, periodic table provided. Foundation tier covers grades 1 to 5 and Higher tier grades 4 to 9. Check your exam board's timetable for dates.
What score do I need to pass the GCSE Chemistry exam?
Grade 4 is a standard pass and grade 5 a strong pass. Boundaries are set after every exam series, so aim for 70% in practice. The exam has aqa: 2 written papers, 100 marks each (200 marks in total), foundation or higher tier and a time limit of 3 hours 30 minutes in total (2 × 1 hour 45 minutes).
What are the most tested topics?
The outline covers atomic structure and the periodic table, bonding, structure and properties, quantitative chemistry, chemical changes and energy changes, rates and equilibrium, organic chemistry and chemical analysis, the atmosphere and using resources. Use the free practice test to see which ones you need most.
The premium GCSE Chemistry study path
Premium GCSE Chemistry prep is studied one topic at a time. Each step starts with that topic's key notes and flashcard deck, then its own question sets of 25, so you master one topic before you move to the next. When every topic is strong, the 6 full mock exams show you're ready.
Your step-by-step study path
- 1Atomic Structure and the Periodic Table9 key notes, 115 flashcards, then 450 practice questions in 18 sets of 25Notes free with an account
- 2Bonding, Structure and Properties9 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 3Quantitative Chemistry9 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 4Chemical Changes and Energy Changes9 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 5Rates and Equilibrium8 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 6Organic Chemistry and Chemical Analysis8 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 7The Atmosphere and Using Resources8 key notes, 110 flashcards, then 425 practice questions in 17 sets of 25Premium
- Final step: 6 full mock exams50 questions each, timed like exam day. Hit your target on them before your first paper.Premium
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Summarised from the exam boards' published specifications and the rules cited, checked November 2026. Confirm current requirements with AQA, Pearson Edexcel and OCR.