AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
The nucleus undergoing fission splits into two smaller nuclei, roughly…
Full specification wording
Nuclear fission: The nucleus undergoing fission splits into two smaller nuclei, roughly equal in size, and emits two or three neutrons plus gamma rays.
The products of a single fission are worth learning as a set.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 3 of 9
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
The products of a single fission are worth learning as a set. The nucleus splits into two smaller nuclei that are roughly equal in size, though not identical; alongside them two or three neutrons are released; and gamma rays are emitted as the excited fragments settle. Energy is released, carried mostly as kinetic energy of the fragments and neutrons. In a fill-in-the-blank question the vocabulary must be exact: energy is released from uranium nuclei, the uranium splits and releases neutrons, and the electromagnetic radiation emitted is gamma rays. Getting 'neutrons' and 'nuclei' the right way round is what the question is actually testing, and gamma, not X-rays, is the radiation named.
What earns the marks
- Two smaller nuclei, roughly equal in size, as the products of the split.
- Two or three neutrons released.
- Gamma rays as the electromagnetic radiation emitted.
- Placing the words in the correct order in a fill-in question: nuclei, then neutrons, then gamma rays.
Common mistakes and how to put them right
Writing electrons or protons where the answer is neutrons.
Saying the nucleus splits into two exactly equal halves with identical mass numbers.
Naming X-rays instead of gamma rays as the radiation emitted.
Describing only the two daughter nuclei and omitting the neutrons.
Writing 'gamma waves' or 'gamma particles' rather than gamma rays.
Exam tips
- In a word-selection question, read all the blanks before you commit, because the same word list often supplies both 'nuclei' and 'neutrons'.
- Say 'roughly equal in size', which is the specification's own wording, rather than 'identical'.
- List the three products in one sentence so nothing is missed: two nuclei, two or three neutrons, gamma rays.
Try the lesson
The start of the Nuclear fission: The nucleus undergoing fission splits into two smaller nuclei, roughly equal in size, and emits two or three neutrons plus gamma rays. lesson, made from checked teaching notes for this specification point.
Have a go first
When a nucleus undergoes fission, what happens to the nucleus?
Listen
The products of a single fission are worth learning as a set. The nucleus splits into two smaller nuclei that are roughly equal in size, though not identical; alongside them two or three neutrons are released; and gamma rays are emitted as the excited fragments settle. Energy is released, carried mostly as kinetic energy of the fragments and neutrons. In a fill-in-the-blank question the vocabulary must be exact: energy is released from uranium nuclei, the uranium splits and releases neutrons, and the electromagnetic radiation emitted is gamma rays. Getting 'neutrons' and 'nuclei' the right way round is what the question is actually testing, and gamma, not X-rays, is the radiation named. A strong answer earns marks for these points. two smaller nuclei, roughly equal in size, as the products of the split. two or three neutrons released. gamma rays as the electromagnetic radiation emitted. placing the words in the correct order in a fill-in question: nuclei, then neutrons, then gamma rays. Exam tip: In a word-selection question, read all the blanks before you commit, because the same word list often supplies both 'nuclei' and 'neutrons'.
See it
Key words
Say what each word means before you turn the card.
two or three neutrons
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gamma rays emitted
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roughly equal fragments
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See every definition
- two or three neutrons
- Released alongside the two smaller nuclei when the nucleus undergoing fission splits.
- gamma rays emitted
- The electromagnetic radiation emitted as the excited fragments settle after the nucleus splits.
- roughly equal fragments
- The two smaller nuclei the nucleus splits into, roughly equal in size, though not identical.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
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