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WJEC GCSE Chemistry (Wales): complete guide to the units, the topics and the exams

A complete guide to WJEC GCSE Chemistry for Wales. Covers Unit 1 and Unit 2 and all twelve topic areas, how the two written papers and the practical assessment are structured and marked, the Foundation and Higher tiers, the maths skills, and how to study each topic for top grades.

Browse guides →Syllabus dot points (34)

WJEC GCSE Chemistry is the chemistry qualification taken in Wales. It is assessed by two written papers (Unit 1 and Unit 2) and a practical assessment (Unit 3). This page is the index: below is a map of the twelve topic areas, the exam structure, the tiers, the practical work and how to study, with a direct link to every dot point.

The two units

The specification content is organised into two units, each with six topic areas. The early topics build the particle, atomic and bonding ideas that everything else depends on.

Unit 1 - Chemical substances, reactions and essential resources covers the nature of substances and chemical reactions, atomic structure and the Periodic Table, water, the ever-changing Earth, rate of chemical change, and limestone. The atomic and reaction ideas here are split across two of our modules. Start with the Substances and atomic structure overview.

Unit 2 - Chemical bonding, application of chemical reactions and organic chemistry covers bonding, structure and properties; acids, bases and salts; metals and their extraction; chemical reactions and energy; crude oil, fuels and organic chemistry; and reversible reactions, industrial processes and important chemicals.

The seven study modules

We group the twelve WJEC topic areas into seven coherent modules, each with an overview guide, a quiz and a set of focused answer pages.

1. Substances and atomic structure (Unit 1.1 to 1.2). Elements, compounds and mixtures, equations and conservation of mass, chromatography, atomic structure and isotopes, electronic structure, and the Periodic table and groups. Start with the Substances and atomic structure overview.

2. Bonding, structure and properties (Unit 2.1). Ionic, covalent, giant covalent and metallic bonding, alloys, and how structure explains properties. Start with the Bonding, structure and properties overview.

3. Rates, energy and equilibria (Unit 1.5, 2.4 and 2.6). Rates of reaction and collision theory, factors affecting rate and catalysts, energy changes and reaction profiles, bond energy calculations, reversible reactions and equilibrium, and the Haber and Contact processes. Start with the Rates, energy and equilibria overview.

4. Acids, salts and analysis (Unit 2.2). Acids, bases and the pH scale, neutralisation and reactions of acids, preparing salts, and chemical tests for gases, cations and anions. Start with the Acids, salts and analysis overview.

5. Metals and their extraction (Unit 2.3). The reactivity series and displacement, extraction of metals and the blast furnace, electrolysis and the extraction of aluminium, and alloys and recycling. Start with the Metals and their extraction overview.

6. The Earth, atmosphere and resources (Unit 1.3, 1.4 and 1.6). Water treatment and solubility, the Earth's atmosphere and its evolution, climate change and air quality, and limestone and its uses. Start with the Earth, atmosphere and resources overview.

7. Crude oil and organic chemistry (Unit 2.5). Crude oil and fractional distillation, alkanes, alkenes and cracking, alcohols and ethanol, and polymers and plastics. Start with the Crude oil and organic chemistry overview.

Exam structure

WJEC GCSE Chemistry is assessed by two written papers and a practical assessment.

  • Unit 1 (Chemical substances, reactions and essential resources) is a written paper of 1 hour 45 minutes, worth 80 marks and 45% of the qualification. It covers topics 1.1 to 1.6.
  • Unit 2 (Chemical bonding, application of chemical reactions and organic chemistry) is a written paper of 1 hour 45 minutes, worth 80 marks and 45% of the qualification. It covers topics 2.1 to 2.6.
  • Unit 3 is a practical assessment worth 10% of the qualification, assessing planning, carrying out, analysing and evaluating an experiment.

Each written paper mixes short-answer and structured questions with extended-response questions, and practical-style questions appear throughout.

Foundation and Higher tiers

The qualification is tiered. You sit both written papers at one tier.

  • Foundation tier targets grades C to G and covers the core content of all the topics.
  • Higher tier targets grades A* to D and adds harder calculations and more demanding ideas, such as bond energy calculations, quantitative work and more analytical evaluation of data.

The tier you enter caps the maximum grade available, so plan with your teacher which tier matches your target grade.

Practical work

The Unit 3 practical assessment is worth 10% and tests an experiment from planning through to analysis and evaluation. Beyond Unit 3, the written papers also test the standard methods from the specified practical work, such as paper chromatography, soap titrations for water hardness, rates-of-reaction experiments, preparing salts, identifying ions by chemical tests, electrolysis and energy-change measurements. Learn each method, the apparatus and how to analyse and evaluate data.

How to study WJEC Chemistry

WJEC Chemistry rewards precise recall, confident calculation and clear explanation.

  1. Work from the specification content. Each statement is a checklist; questions are written from them.
  2. Learn definitions and equations. Mark schemes reward precise wording and the recall of equations.
  3. Drill the maths. Relative atomic mass, balancing equations, rates and bond energy calculations must be automatic.
  4. Master the practical methods. Standard methods and data analysis recur across both papers and Unit 3.
  5. Practise extended-response questions. They reward a logical, well-linked argument and the right WJEC command word response.

Syllabus, dot point by dot point

Each module has specification-level answer pages with worked exam questions and cross-links, plus an overview guide and quiz. Browse the full set at /wjec-gcse/chemistry/syllabus.

Module 1 - Substances and atomic structure

Module 2 - Bonding, structure and properties

Module 3 - Rates, energy and equilibria

Module 4 - Acids, salts and analysis

Module 5 - Metals and their extraction

Module 6 - The Earth, atmosphere and resources

Module 7 - Crude oil and organic chemistry

For the official specification

WJEC publishes the full specification, past papers and mark schemes at wjec.co.uk. Always revise from the current specification and WJEC's own past papers, because question style is board-specific.

Chemistry guides

In-depth written guides with paired practice quizzes.

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Chemistry practice quizzes

Multiple-choice drills with worked answer explanations. Your scores stay on this device.

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Common questions about Chemistry

How is WJEC GCSE Chemistry structured?
WJEC GCSE Chemistry is assessed by two written papers and a practical assessment. Unit 1 (Chemical substances, reactions and essential resources) covers topics 1.1 to 1.6, and Unit 2 (Chemical bonding, application of chemical reactions and organic chemistry) covers topics 2.1 to 2.6. Unit 1 and Unit 2 are each a 1 hour 45 minute written paper worth 80 marks and 45 percent of the qualification. Unit 3 is a practical assessment worth 10 percent.
What are the WJEC GCSE Chemistry exam papers?
There are two written papers and one practical assessment. Unit 1 is a written paper of 1 hour 45 minutes worth 80 marks (45 percent), covering the nature of substances, atomic structure and the Periodic Table, water, the ever-changing Earth, rate of chemical change and limestone. Unit 2 is a written paper of 1 hour 45 minutes worth 80 marks (45 percent), covering bonding and structure, acids bases and salts, metals and extraction, energy changes, organic chemistry, and reversible reactions and industrial processes. Unit 3 is a practical assessment worth 10 percent.
What is the difference between Foundation and Higher tier in WJEC Chemistry?
WJEC GCSE Chemistry is tiered. Foundation tier targets grades C to G and Higher tier targets grades A* to D. You sit both written papers at the same tier, and the most demanding content (such as harder calculations and some quantitative and analytical work) sits on Higher only. The tier you enter caps the maximum grade available.
How much maths and practical work is in WJEC Chemistry?
A significant share of marks assesses mathematical skills, including relative atomic mass, balancing equations, reacting ideas, rates, energy changes from bond energies and interpreting data. The Unit 3 practical assessment is worth 10 percent and tests planning, carrying out, analysing and evaluating an experiment, and practical-style questions also appear within the Unit 1 and Unit 2 written papers, so you must learn the standard methods and how to handle data.
How is WJEC Chemistry different from Eduqas Chemistry?
WJEC and Eduqas are sister boards. WJEC GCSE Chemistry is the specification used in Wales, while Eduqas is the equivalent used in England. The chemistry content overlaps heavily, but the unit titles, assessment structure (WJEC uses Unit 1, Unit 2 and a practical Unit 3) and grading context differ, so always revise from the WJEC specification and WJEC past papers if you are sitting WJEC in Wales.
How should I structure my WJEC Chemistry revision?
Work topic by topic against the specification content, because questions are written directly from it. Learn definitions, formulae and equations precisely, drill the calculations (relative atomic mass, balancing, rates, bond energies) until they are automatic, and practise the prescribed practical methods. Use WJEC past papers to rehearse the structured and extended-response questions across both units, watching for command words such as Describe, Explain, Calculate and Evaluate.
What's the difference between ionic and covalent bonding?
Ionic: electrons are transferred between atoms (typically metal + non-metal); forms a lattice. Covalent: electrons are shared (non-metal + non-metal); forms discrete molecules or networks.
How do I calculate pH?
pH = -log₁₀[H⁺]. For strong acids/bases, [H⁺] equals the concentration. For weak acids, use Ka. For buffers, use Henderson-Hasselbalch.
What's Le Chatelier's principle?
When a system at equilibrium is disturbed (concentration, temperature, pressure change), the equilibrium shifts to partially counteract the disturbance.
How do I balance a redox equation?
Identify the half-reactions (oxidation and reduction), balance atoms (excluding O and H), balance O with H₂O and H with H⁺, balance charge with electrons, then combine so electrons cancel.
What's the difference between enthalpy and entropy?
Enthalpy (ΔH) is the heat change of a reaction. Entropy (ΔS) is the change in disorder. Gibbs free energy (ΔG = ΔH - TΔS) tells you if the reaction is spontaneous.