Pearson Edexcel · GCSE · Physics
Course version: 1PH0 · Version from Sept 2016
Recall that nuclei that have undergone radioactive decay often undergo…
Full specification wording
Topic 6 – Radioactivity: 6.21 Recall that nuclei that have undergone radioactive decay often undergo nuclear rearrangement with a loss of energy as gamma radiation
After alpha or beta decay, a nucleus is frequently left in an excited state, meaning its protons and neutrons sit in a higher-energy arrangement than the most stable one.
Checked against the Pearson Edexcel 1PH0 specification (opens in a new tab) on .
- Point 20 of 42
Study notes
From the checked teaching notes for this specification point.
The idea
After alpha or beta decay, a nucleus is frequently left in an excited state, meaning its protons and neutrons sit in a higher-energy arrangement than the most stable one. The nucleus then rearranges internally and releases the surplus energy as a gamma photon. This gamma emission changes neither the mass number nor the atomic number, because the number of protons and neutrons stays the same; only their arrangement and energy state alter. For example, a nucleus that has just emitted a beta particle may still hold excess energy, so it settles by emitting gamma radiation. Recognise that gamma emission usually accompanies alpha or beta decay rather than occurring alone, and that it carries away energy without changing the element.
What earns the marks
- States that gamma radiation is emitted as a nucleus loses surplus energy after radioactive decay.
- Recognises that gamma emission follows alpha or beta decay as the nucleus rearranges.
- Confirms that gamma emission leaves the mass number and atomic number unchanged.
- Identifies gamma radiation as the energy loss accompanying nuclear rearrangement.
Common mistakes and how to put them right
Claims that gamma emission changes the element.
Put it right by noting the proton number stays the same.
Assumes gamma emission occurs on its own without prior decay.
Put it right by linking it to rearrangement after alpha or beta decay.
States that gamma emission removes a particle from the nucleus.
Put it right by explaining that only energy is released.
Exam tips
- Read the question for the word 'recall' and choose the option that matches the taught statement exactly.
- Eliminate options that change the mass number or atomic number, since gamma emission alters neither.
- Link gamma emission to a nucleus settling after alpha or beta decay when comparing options.
Try the lesson
The start of the Topic 6 – Radioactivity: 6.21 Recall that nuclei that have undergone radioactive decay often undergo nuclear rearrangement with a loss of energy as gamma radiation lesson, made from checked teaching notes for this specification point.
Have a go first
After alpha or beta decay, a nucleus may be left with surplus energy. In what form is this energy usually released?
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