What does the Substances and atomic structure module cover?

This module gathers the substances and atomic content of Chemistry 1 in WJEC GCSE Science Double Award. It covers classifying elements, compounds and mixtures and reading formulae, word and balanced symbol equations and conservation of mass, the structure of the atom, isotopes and relative atomic mass, electronic structure, and the trends in Groups 1, 7 and 0 of the Periodic Table.

Which unit and paper assess this module?

These topics are part of Unit 2 (Chemistry 1), a written paper of 1 hour 15 minutes worth 15 percent of the Double Award qualification, sat at Foundation or Higher tier. Questions mix recall, calculation and explanation.

What maths skills are needed here?

You need to balance symbol equations, apply conservation of mass to find a missing mass, count atoms in formulae, work out the numbers of protons, neutrons and electrons, and calculate relative atomic mass as a weighted mean from isotopic abundances.

What kinds of question come up?

Expect questions classifying substances, reading and balancing formulae and equations, explaining conservation of mass and apparent mass changes, counting sub-atomic particles, defining and using isotopes, writing electronic structures, and explaining the reactivity trends in Groups 1 and 7 and the inertness of Group 0.

How should I revise this module?

Learn the definitions of element, compound and mixture and the signs of a chemical reaction. Drill balancing equations and conservation-of-mass calculations. Memorise the relative masses and charges of the sub-atomic particles, the shell-filling rules and the electronic structures of the first twenty elements, and the Group 1, 7 and 0 trends with their electron explanations. Use WJEC Double Award past papers.

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WJEC GCSE Science Double Award: Substances and atomic structure (Unit 2, Chemistry 1) overview

An overview of the Substances and atomic structure module in WJEC GCSE Science Double Award (Unit 2, Chemistry 1), mapping elements, compounds and mixtures, chemical reactions and equations, atomic structure and isotopes, electronic structure, and the Periodic Table and its groups.

Generated by Claude Opus 4.86 min readDouble Award Unit 2 (Chemistry 1)Updated 2026-06-15

Reviewed by: AI editorial process; not yet individually human-reviewed

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The topics in this module
How this module fits the exam
How to study this module

The Substances and atomic structure module gathers the substances and atomic content of Chemistry 1 in WJEC GCSE Science Double Award. It introduces the language of chemistry, how reactions are represented, and the structure of the atom that explains the whole Periodic Table. Everything later in the chemistry course builds on these ideas. This page maps the module and links to a focused answer page for each part.

The topics in this module

Elements, compounds and mixtures: Classifying substances, reading formulae, and telling physical changes from chemical reactions. See Elements, compounds and mixtures.
Chemical reactions and equations: Word and balanced symbol equations, state symbols, and conservation of mass. See Chemical reactions and equations.
Atomic structure and isotopes: Sub-atomic particles, atomic and mass number, isotopes and relative atomic mass. See Atomic structure and isotopes.
Electronic structure: How electrons fill shells and how the structure links to group and period. See Electronic structure.
The Periodic Table and groups: The arrangement of the table, metals and non-metals, and the trends in Groups 1, 7 and 0. See The Periodic Table and groups.

How this module fits the exam

These topics sit in Unit 2 (Chemistry 1), a written paper of 1 hour 15 minutes worth 15%. Questions mix recall (definitions, trends), skills (balancing) and calculation (conservation of mass, relative atomic mass).

How to study this module

Nail the vocabulary. Element, compound, mixture, reactant, product, isotope - precise definitions earn marks.
Drill balancing. Practise putting numbers in front of formulae until balancing is automatic.
Learn the particle facts. Relative masses and charges, and how to find each from atomic and mass number.
Memorise shell filling. 2, 8, 8 for the first twenty elements, and how the structure gives group and period.
Learn the group trends. Group 1 more reactive down, Group 7 less reactive down, Group 0 inert.

Then test yourself with the module quiz.

Sources & how we know this

WJEC GCSE Science (Double Award) specification (from 2016) — WJEC (2016)