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Unit 2 Chemistry 1: Substances and atomic structure

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

What is inside an atom, and how do isotopes give an element its relative atomic mass?

Sub-atomic particles and their relative masses and charges, working out particle numbers from atomic and mass number, isotopes, and calculating relative atomic mass.
A focused answer to the WJEC GCSE Science Double Award Unit 2 topic on atoms, covering protons, neutrons and electrons and their relative masses and charges, atomic and mass number, particles in atoms and ions, isotopes, and calculating relative atomic mass.
9 min answer →

How do we write word and balanced symbol equations, and why is mass conserved in a reaction?

Word and balanced symbol equations with state symbols, the law of conservation of mass, and explaining apparent mass changes.
A focused answer to the WJEC GCSE Science Double Award Unit 2 topic on equations, covering word and balanced symbol equations with state symbols, the law of conservation of mass, and explaining apparent gains or losses in mass.
10 min answer →

How are electrons arranged in shells, and how does this link to the Periodic Table?

How electrons fill shells, the electronic structures of the first twenty elements, and linking outer electrons to group and shells to period.
A focused answer to the WJEC GCSE Science Double Award Unit 2 topic on electronic structure, covering how electrons fill shells, the electronic structures of the first twenty elements, and how the structure links to an element's group and period.
9 min answer →

What is the difference between an element, a compound and a mixture, and how do we tell a chemical reaction has happened?

Classifying substances as elements, compounds or mixtures, reading chemical formulae, and distinguishing physical changes from chemical reactions.
A focused answer to the WJEC GCSE Science Double Award Unit 2 topic on substances, covering how to classify elements, compounds and mixtures, read chemical formulae, and tell a physical change from a chemical reaction using evidence.
9 min answer →

How is the Periodic Table arranged, and what are the trends in Groups 1, 7 and 0?

The arrangement of the Periodic Table into groups and periods, metals and non-metals, and the trends in reactivity in Group 1, Group 7 and Group 0.
A focused answer to the WJEC GCSE Science Double Award Unit 2 topic on the Periodic Table, covering its arrangement into groups and periods, metals and non-metals, and the trends in Group 1 (alkali metals), Group 7 (halogens) and Group 0 (noble gases).
9 min answer →