GCSE Physics: Nuclear equations

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1. What process do nuclear equations represent?

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   Radioactive decay — the change in a nucleus when it emits nuclear radiation.

2. What symbol represents an alpha particle in a nuclear equation?

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   ⁴₂He — a helium nucleus with mass number 4 and atomic number (charge) 2.

3. What symbol represents a beta particle in a nuclear equation?

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   ⁰₋₁e — an electron with mass number 0 and charge −1.

4. In a nuclear equation, an alpha particle is written as a ? nucleus.

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   helium

5. By how much does the mass number of a nucleus change in alpha decay?

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   It decreases by 4, because the alpha particle carries away 2 protons and 2 neutrons.

6. By how much does the atomic number of a nucleus change in alpha decay?

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   It decreases by 2, because the alpha particle carries away 2 protons.

7. How does the mass number of a nucleus change in beta decay?

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   It does not change — the emitted electron has negligible mass (mass number 0).

8. How does the atomic number of a nucleus change in beta decay?

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   It increases by 1, because a neutron changes into a proton as the electron is emitted.

9. What effect does emitting a gamma ray have on the mass and charge of a nucleus?

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   None — neither the mass nor the charge of the nucleus changes.

10. Which two quantities must balance on both sides of a nuclear equation?

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    The mass numbers and the atomic numbers.

11. Alpha decay causes both the mass and the ? of the nucleus to decrease.

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    charge