GCSE Chemistry
Chemical Changes
Chemical Changes is a core strand in Chemistry. Work through the topics below in any order, or follow your course — each guide includes explanations, common mistakes and exam-style practice.
Topic guides
Reactivity Series
The reactivity series is a list of metals arranged in order of their reactivity, from most reactive to least reactive.
Open guideMetal Extraction
Metal extraction is the process of obtaining a metal from its ore, which is a naturally occurring rock containing the metal compound.
Open guideOxidation, Reduction & Redox
Oxidation and reduction are chemical processes that always happen together, which is why they are often called redox reactions.
Open guideAcids & Alkalis
Acids are substances that produce hydrogen ions (H⁺) when dissolved in water.
Open guideMaking Salts
A salt is a chemical compound formed from the reaction of an acid with a base.
Open guidepH and Neutralisation
The pH scale measures the acidity or alkalinity of a solution.
Open guideElectrolysis
Electrolysis is the process of breaking down an ionic compound, either molten or in solution, by passing an electric current through it.
Open guideElectrolysis of Aqueous Solutions
When an ionic compound is dissolved in water, the water itself can also be broken down during electrolysis.
Open guideFuel Cells
A fuel cell is an electrochemical cell that generates electricity through a chemical reaction between a fuel (like hydrogen) and an oxidant (like oxygen).
Open guide
Revision strategy
Students often slip on the details explained in our guides — read the “common mistakes” section in each topic.
- Alternate between reading a guide and doing timed questions — don’t only re-read notes.
- Return to this hub anytime; new guides appear automatically as we publish them.