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WJEC A-Level Chemistry: complete guide to the four units and the exams

A complete guide to WJEC A-Level Chemistry (Wales). Covers the four examined theory units (The Language of Chemistry, Structure and Physical Chemistry; Energy, Rate and Chemistry of Carbon Compounds; Physical and Inorganic Chemistry; Organic Chemistry and Analysis), the practical work, how the AS and A2 papers are structured and marked, and how to study each unit for top grades.

Browse guides →Syllabus dot points (30)

WJEC A-Level Chemistry (Wales) is a two-year course with an AS year and an A2 year, assessed by written unit papers and a practical examination. This page is the index: below is a map of the four content units, the exam structure, and how to study each one.

The four WJEC Chemistry units

The specification organises the content into four examined theory units. Units 1 and 2 are the AS content and first year; Units 3 and 4 are the A2 content.

Unit 1 The Language of Chemistry, Structure and Physical Chemistry
Formulae and equations, basic ideas about atoms, chemical calculations, bonding, solid structures, the periodic table, and simpler equilibria and acid-base reactions.
Unit 2 Energy, Rate and Chemistry of Carbon Compounds
Thermochemistry, rates of reaction, the wider impact of chemistry, organic compounds, hydrocarbons, halogenoalkanes, and alcohols and carboxylic acids.
Unit 3 Physical and Inorganic Chemistry
Redox and standard electrode potential, redox reactions, chemistry of the p-block, chemistry of the d-block, chemical kinetics, enthalpy, entropy and free energy, equilibria, and acid-base equilibria.
Unit 4 Organic Chemistry and Analysis
Stereoisomerism, aromaticity, alcohols and phenols, aldehydes and ketones, carboxylic acids and their derivatives, amines and amino acids, organic synthesis and analysis, and spectroscopy and chromatography.

Exam structure

WJEC A-Level Chemistry is assessed by written unit papers and a practical examination. A calculator is allowed in every written paper, and a periodic table and data are provided.

  • Unit 1 The Language of Chemistry, Structure and Physical Chemistry - AS written paper of structured questions and extended responses.
  • Unit 2 Energy, Rate and Chemistry of Carbon Compounds - AS written paper of structured questions and extended responses.
  • Unit 3 Physical and Inorganic Chemistry - A2 written paper at higher demand.
  • Unit 4 Organic Chemistry and Analysis - A2 written paper at higher demand.
  • Practical examination - assesses experimental and analytical skills separately from the written papers.

A large share of marks assess maths skills, and the specified practical tasks recur across the written papers and the practical examination.

How to study WJEC Chemistry

Chemistry rewards accurate calculation, precise definitions and confident mechanism work.

  1. Work from the specification statements. Each statement is a checklist; questions are written from them.
  2. Drill the calculations. Moles, titrations, enthalpy cycles, rate equations, KcK_c, KpK_p, pH and KaK_a, Gibbs free energy and electrode potentials must be automatic.
  3. Learn definitions exactly. Mark schemes reward precise terms, such as first ionisation energy, activation energy, standard enthalpy of formation, and the Bronsted-Lowry definition.
  4. Master organic mechanisms and maps. Learn each reaction by reagents, conditions, mechanism and product, and build reaction maps that connect functional groups.
  5. Practise inorganic tests and analysis. Flame tests, precipitate and gas tests, and the interpretation of mass spectra, infrared and NMR underpin Unit 4.

The four units, topic by topic

Each unit has topic-level overviews with worked exam questions and cross-links, plus dot-point answer pages for each specification statement.

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.

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Chemistry practice quizzes

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The WJEC-A-LEVEL system, explained

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Common questions about Chemistry

How is WJEC A-Level Chemistry structured?
WJEC A-Level Chemistry is a two-year course with an AS year and an A2 year. The AS comprises Unit 1 (The Language of Chemistry, Structure and Physical Chemistry) and Unit 2 (Energy, Rate and Chemistry of Carbon Compounds), each examined by a written paper. The A2 adds Unit 3 (Physical and Inorganic Chemistry) and Unit 4 (Organic Chemistry and Analysis), each a written paper. Practical skills are assessed by a separate practical examination. The qualification follows the 2015 WJEC specification used in Wales.
What are the WJEC A-Level Chemistry exam papers?
At AS, Unit 1 (The Language of Chemistry, Structure and Physical Chemistry) and Unit 2 (Energy, Rate and Chemistry of Carbon Compounds) are each a written paper of structured and extended questions. At A2, Unit 3 (Physical and Inorganic Chemistry) and Unit 4 (Organic Chemistry and Analysis) are each a written paper at a higher demand. A separate practical examination assesses experimental skills. AS marks count towards the AS qualification, and A2 work completes the full A-level.
How much maths is in WJEC A-Level Chemistry?
A large share of the marks assess mathematical skills. Expect moles and concentration calculations, empirical and molecular formulae, titration and back-titration arithmetic, enthalpy and Hess cycles, rate orders and rate constants, equilibrium constants Kc and Kp, pH and Ka, Gibbs free energy, electrode potentials and atom economy. A calculator is allowed in every written paper.
How is practical work assessed in WJEC A-Level Chemistry?
Practical skills are assessed by a separate practical examination rather than continuous coursework, and the specified practical tasks also appear in the written papers. Core techniques include titrations, making a standard solution, measuring enthalpy changes by calorimetry, rates experiments, qualitative inorganic and organic tests, and organic preparation, purification and recrystallisation. You must be able to plan, carry out, analyse and evaluate experiments.
How should I structure my WJEC A-Level Chemistry revision?
Work unit by unit against the specification statements, because questions are written directly from them. Chemistry rewards accurate calculation and precise definitions, so drill moles, titrations, enthalpy cycles, rate equations, Kc, Kp, pH and electrode potentials until they are automatic, and learn definitions and mechanisms exactly. Practise the organic reaction maps and the inorganic tests, and rehearse spectroscopy interpretation for Unit 4.
How does WJEC A-Level Chemistry compare to other exam boards?
All A-Level Chemistry specifications cover the same regulated core, so atomic structure, bonding, energetics, kinetics, equilibria, organic chemistry and analysis appear everywhere. WJEC's distinctive features are its four-unit structure, the wider impact of chemistry topic in Unit 2, and its own list of specified practical tasks and qualitative tests. WJEC and Eduqas share much content, but always revise from the current WJEC specification and WJEC past papers, because question style is board-specific.
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.