AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
Cells contain chemicals which react to produce electricity.
Full specification wording
Cells and batteries: Cells contain chemicals which react to produce electricity.
A cell is a device that converts chemical energy into electrical energy.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 1 of 7
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A cell is a device that converts chemical energy into electrical energy. Inside a simple cell, two different metals act as electrodes in contact with an electrolyte. The more reactive metal tends to lose electrons and is oxidised, while the less reactive metal provides a surface where electrons are gained and reduction occurs. These electron transfers happen at separate electrodes, so electrons flow through the external circuit as an electric current. The chemical reaction continues until one reactant is used up, which is why cells eventually run down. A battery consists of two or more cells connected together in series, giving a larger voltage.
For example: A zinc–copper cell with a salt solution electrolyte produces a voltage because zinc is more reactive than copper.
What earns the marks
- State that a cell converts chemical energy into electrical energy.
- Describe that the chemical reaction involves electron transfer between electrodes.
- Explain that oxidation occurs at the more reactive electrode and reduction at the less reactive electrode.
- Recognise that electrons flow through the external circuit, producing an electric current.
- Link the cell running down to the reaction stopping when a reactant is used up.
Common mistakes and how to put them right
Saying that cells store electricity rather than converting chemical energy into electrical energy.
Put it right by describing the energy transfer.
Believing that electrons travel through the electrolyte rather than the external circuit.
Put it right by stating that ions move in the electrolyte while electrons flow in the wires.
Thinking that a single cell and a battery are the same.
Put it right by stating that a battery contains two or more cells connected together.
Exam tips
- Use the phrase chemical energy transferred to electrical energy when describing a cell.
- Refer to the more reactive metal as the negative electrode in a simple cell unless told otherwise.
- When explaining why a cell stops working, link it to the reactant being used up rather than to electrons running out.
Try the lesson
The start of the Cells and batteries: Cells contain chemicals which react to produce electricity. lesson, made from checked teaching notes for this specification point.
Have a go first
How does a simple chemical cell produce electricity?
Listen
A cell is a device that converts chemical energy into electrical energy. Inside a simple cell, two different metals act as electrodes in contact with an electrolyte. The more reactive metal tends to lose electrons and is oxidised, while the less reactive metal provides a surface where electrons are gained and reduction occurs. These electron transfers happen at separate electrodes, so electrons flow through the external circuit as an electric current. The chemical reaction continues until one reactant is used up, which is why cells eventually run down. A battery consists of two or more cells connected together in series, giving a larger voltage. For example, a zinc–copper cell with a salt solution electrolyte produces a voltage because zinc is more reactive than copper. A strong answer earns marks for these points. State that a cell converts chemical energy into electrical energy. Describe that the chemical reaction involves electron transfer between electrodes. Explain that oxidation occurs at the more reactive electrode and reduction at the less reactive electrode. Recognise that electrons flow through the external circuit, producing an electric current. A common slip: Saying that cells store electricity rather than converting chemical energy into electrical energy. Instead, describing the energy transfer. Exam tip: Use the phrase chemical energy transferred to electrical energy when describing a cell.
See it
Put it in order
Put these steps in the order they happen.
- 1. Cell runs down
- 2. Reaction continues until a reactant is used up
- 3. Electrons flow through external circuit
- 4. Electrical energy produced
- 5. Chemical energy in cell
- 6. More reactive metal electrode: loses electrons, oxidised
- 7. Less reactive metal electrode: electrons gained, reduction
Key words
Say what each word means before you turn the card.
Cell
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Battery
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Oxidation
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Reduction
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See every definition
- Cell
- A device that converts chemical energy into electrical energy, containing chemicals which react to produce electricity.
- Battery
- Consists of two or more cells connected together in series, giving a larger voltage.
- Oxidation
- Occurs at the more reactive metal electrode, which tends to lose electrons.
- Reduction
- Occurs at the less reactive metal, which provides a surface where electrons are gained.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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