AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
Students should be able to use the names and symbols of common nuclei and…
Full specification wording
Nuclear equations: Students should be able to use the names and symbols of common nuclei and particles to write balanced equations that show single alpha (α) and beta (β) decay.
Work through a decay equation in a fixed order.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 4 of 6
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Work through a decay equation in a fixed order. Copy the original nucleus with both its numbers. Write the emitted particle in full, ⁴₂He for alpha or ⁰₋₁e for beta. Then use the two conservation rules to fill in the daughter nucleus. Alpha: ²²⁶₈₈Ra → ²²²₈₆Rn + ⁴₂He, where 222 + 4 = 226 and 86 + 2 = 88. Beta: ²¹⁴₈₂Pb → ²¹⁴₈₃Bi + ⁰₋₁e, where 214 + 0 = 214 and 83 + (-1) = 82. The same method run backwards identifies the radiation emitted: if the atomic number rose by one and the mass number held still, the decay was beta. Single decay means one particle, so do not add a second.
What earns the marks
- Each correct missing mass number in the completed equation.
- Each correct missing atomic number in the completed equation.
- Writing the emitted particle with its own mass number and atomic number, ⁴₂He or ⁰₋₁e.
- Naming the type of decay from the way the numbers changed, for example beta because the proton number rose by one.
Common mistakes and how to put them right
Leaving the emitted particle out of the equation altogether.
Balancing the mass numbers and forgetting to balance the atomic numbers.
Writing the word alpha in place of the symbol when the question asks for an equation.
Showing both an alpha and a beta particle when the question specifies a single decay.
Exam tips
- Fill in the emitted particle first; the daughter nucleus then follows from subtraction.
- Set the numbers out in two columns so the totals can be checked at a glance.
- Give the reason as well as the name when identifying a decay type, since the reason usually carries the second mark.
Try the lesson
The start of the Nuclear equations: Students should be able to use the names and symbols of common nuclei and particles to write balanced equations that show single alpha (α) and beta (β) decay. lesson, made from checked teaching notes for this specification point.
Have a go first
Which particle is represented by the symbol ⁴₂α in a nuclear equation?
Listen
Work through a decay equation in a fixed order. Copy the original nucleus with both its numbers. Write the emitted particle in full, ⁴₂He for alpha or ⁰₋₁e for beta. Then use the two conservation rules to fill in the daughter nucleus. Alpha: ²²⁶₈₈Ra → ²²²₈₆Rn + ⁴₂He, where 222 + 4 = 226 and 86 + 2 = 88. Beta: ²¹⁴₈₂Pb → ²¹⁴₈₃Bi + ⁰₋₁e, where 214 + 0 = 214 and 83 + (-1) = 82. The same method run backwards identifies the radiation emitted: if the atomic number rose by one and the mass number held still, the decay was beta. Single decay means one particle, so do not add a second. A strong answer earns marks for these points. each correct missing mass number in the completed equation. each correct missing atomic number in the completed equation. writing the emitted particle with its own mass number and atomic number, ⁴₂He or ⁰₋₁e. naming the type of decay from the way the numbers changed, for example beta because the proton number rose by one. Exam tip: Fill in the emitted particle first; the daughter nucleus then follows from subtraction.
Key words
Say what each word means before you turn the card.
balanced nuclear equations
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single alpha decay
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single beta decay
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identifying the emitted particle
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See every definition
- balanced nuclear equations
- Equations written using the names and symbols of common nuclei and particles, in which both the mass numbers and the atomic numbers balance.
- single alpha decay
- Decay in which one alpha particle, written in full as ⁴₂He, is emitted, so a second particle is not added.
- single beta decay
- Decay in which one beta particle, written in full as ⁰₋₁e, is emitted, so a second particle is not added.
- identifying the emitted particle
- Running the same method backwards: if the atomic number rose by one and the mass number held still, the decay was beta.
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Test your understanding of Nuclear equations: Students should be able to use the names and symbols of common nuclei and particles to write balanced equations that show single alpha (α) and beta (β) decay.
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