WJEC GCSE Chemistry: units, papers, grades and 2027 dates

WJEC GCSE Chemistry: the specification

This Qualifications Wales approved GCSE (approval number C00/0779/9) runs from 2016 and was amended in February 2026. The new Unit 3 starts with the 2026 cohort and is first awarded in 2028. WJEC's Chemistry page says the January to February 2027 Unit 3 practical is the legacy version, so Year 10 learners cannot be entered for it. The cover states the qualification is not available to centres in England.

WJEC GCSE Chemistry papers

Expect short answers, structured questions, extended writing and data response, with some questions in a practical setting. WJEC reserves at least 20% of the marks for mathematical skills and at least 15% for scientific enquiry skills in every series. Each paper includes a Periodic Table and a table of common ions, and you need a calculator. Unit 3 is a school-run enquiry marked by WJEC. See our WJEC GCSE timetable 2027 for the full set of dates.

What each Chemistry unit covers

Unit 1: Chemical Substances, Reactions and Essential Resources

• 1.1 The nature of substances and chemical reactions
• 1.2 Atomic structure and the Periodic Table
• 1.3 Water
• 1.4 The ever-changing Earth
• 1.5 Rate of chemical change
• 1.6 Limestone

Unit 2: Chemical Bonding, Application of Chemical Reactions and Organic Chemistry

• 2.1 Bonding, structure and properties
• 2.2 Acids, bases and salts
• 2.3 Metals and their extraction
• 2.4 Chemical reactions and energy
• 2.5 Crude oil, fuels and organic chemistry
• 2.6 Reversible reactions, industrial processes and important chemicals

Content in bold is for Higher tier only. Because the Periodic Table is printed in the paper, you take Ar values from it and do not memorise masses. The table no longer shows mass numbers.

Worked examples in WJEC Chemistry style

Percentage composition by mass

Find the percentage of calcium in calcium carbonate, CaCO₃, using Ar values Ca = 40, C = 12 and O = 16. First the relative formula mass:

Percentage yield and Rf

A reaction should make 5.0 g of a product in theory but 3.8 g is collected. The percentage yield is:

In chromatography, a spot moves 4.2 cm while the solvent front moves 6.0 cm, so Rf is 4.2 over 6.0, which is 0.70. You are expected to recall the Rf expression, and a more soluble substance is carried further up the paper.

WJEC GCSE Chemistry grades

Every unit becomes a uniform mark, the marks are added, and the total gives the grade. Higher tier covers A* to D, Foundation tier covers C to G, and anything below G is unclassified. A Foundation candidate cannot score more than 125 uniform marks in Unit 1 or Unit 2. The published equivalences are:

WJEC resets the raw-mark thresholds in each series and publishes them on results day. A unit can be resat once, with the better result counting, and you need to take at least 40% of the assessment in the series you cash in. For Welsh grading in general, see GCSE grades in Wales.

Use the daily paper as a short timed mock for WJEC GCSE Chemistry

The matching daily papers are GCSE Chemistry Foundation and GCSE Chemistry Higher, each 8 questions and 25 to 35 marks. They are quick mocks written by Uni-Sine, not WJEC.

• What it covers well: atomic structure, bonding, rates of reaction, acids and salts, organic chemistry, moles and reacting masses, electrolysis, energy changes, equilibrium and chemical analysis, which map onto both units.
• What it does not cover: none of its main topics is limestone, the extraction of metals or industrial processes. WJEC past papers will give you those, and the enquiry task is not covered.

Time a daily paper, then redo every calculation you lost marks on by hand with the Periodic Table open. Add a WJEC specimen paper weekly so you practise long balanced-equation and organic questions.

Exam answers

There are no official or past paper answers here. When you finish a daily paper and mark it, the answers and a worked mark scheme for that paper appear alongside it.

Common mistakes in WJEC GCSE Chemistry

• Forgetting state symbols or balancing when asked for a balanced symbol equation. Count each atom on both sides.
• Using mass numbers instead of Ar values from the Periodic Table. The table in the paper no longer shows mass numbers.
• Confusing percentage yield with percentage composition. Yield is actual over theoretical; composition is element mass over Mr.
• Skipping the unit of Rf. It is a ratio with no unit and must be between 0 and 1.

Read next

UK · GCSEWJEC GCSE Chemistry grade boundaries 2026: marks per gradeWJEC's June 2026 GCSE Chemistry boundaries: the fixed UMS totals, raw marks for Units 1 to 3 on both tiers, and the move from 2025.