Half equations: electrolysis
I can write half–equations and balanced ionic equations.
Half equations: electrolysis
I can write half–equations and balanced ionic equations.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- A half–equation describes what happens to one reactant in a reaction, such as the process at an individual electrode.
- Half–equations show balanced charges as well as balanced atoms.
- A balanced ionic equation shows all reacting ions involved in a reaction.
- Ions not involved in a reaction do not appear in a balanced ionic equation.
Keywords
Reduction - a type of reaction in which a substance gains electrons or loses oxygen
Oxidation - a type of reaction in which a substance loses electrons or gains oxygen
Half–equation - a chemical equation used to show the electrons lost in oxidation or the electrons gained in reduction
Ionic equation - a balanced equation showing all the ions involved in a reaction
Spectator ions - the ions not involved in a chemical reaction
Common misconception
Getting the electrons confused; how many and which side of the half equations to write them on.
When writing a half equation, electrons should be added and not taken away and so should go on the side of the equation where they are added. All charges must cancel each other out and the atoms on each side of the equation balance.
To help you plan your year 11 chemistry lesson on: Half equations: electrolysis, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 11 chemistry lesson on: Half equations: electrolysis, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
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Explore more key stage 4 chemistry lessons from the Electrolysis unit, dive into the full secondary chemistry curriculum, or learn more about lesson planning.