Atomic StructureKey Facts

Chain Reactions

Part of Nuclear Fission & FusionGCSE Physics

This key facts covers Chain Reactions within Nuclear Fission & Fusion for GCSE Physics. Revise Nuclear Fission & Fusion in Atomic Structure for GCSE Physics with 13 exam-style questions and 25 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 6 of 18 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 6 of 18

Practice

13 questions

Recall

25 flashcards

⛓️ Chain Reactions

What is a chain reaction?

  • Each fission releases 2-3 neutrons
  • These neutrons can cause more fissions
  • Each of those releases more neutrons → more fissions → exponential growth!

Chain Reaction:

1 fission → 3 neutrons → 3 fissions → 9 neutrons → 9 fissions...

⬤ → ●●● → ⬤⬤⬤ → ●●●●●●●●● → ⬤⬤⬤⬤⬤⬤⬤⬤⬤ → 💥

Numbers: 1 → 3 → 9 → 27 → 81 → 243... (exponential growth!)

Types of chain reaction:

  • Controlled: Nuclear power station — chain reaction maintained at steady rate
  • Uncontrolled: Nuclear bomb — chain reaction grows exponentially → explosion

Keep building this topic

Read this section alongside the surrounding pages in Nuclear Fission & Fusion. That gives you the full topic sequence instead of a single isolated revision point.

Practice Questions for Nuclear Fission & Fusion

What is nuclear fission?

  • A. The joining of two small nuclei to form one larger nucleus
  • B. The spontaneous emission of an alpha particle from a nucleus
  • C. The splitting of a large nucleus into two smaller nuclei
  • D. The absorption of an electron by a nucleus
1 markfoundation

Explain what is meant by a chain reaction in nuclear fission.

2 marksstandard

Quick Recall Flashcards

What is nuclear fission?
The splitting of a large, unstable nucleus into two smaller nuclei, releasing energy and neutrons
What is nuclear fusion?
The joining of two small, light nuclei to form a larger nucleus, releasing energy

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