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Atomic StructureIntroduction

Unstable Nuclei

Part of Radioactive Decay · GCSE GCSE Physics revision

This introduction covers Unstable Nuclei within Radioactive Decay for GCSE Physics. Revise Radioactive Decay in Atomic Structure for GCSE Physics with 15 exam-style questions and 6 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 1 of 14 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 1 of 14

Practice

15 questions

Recall

6 flashcards

⚛️ Unstable Nuclei

Some atomic nuclei are unstable — they have the wrong balance of protons and neutrons, or simply too much energy. These nuclei will spontaneously "decay" by emitting particles or energy to become more stable. You can't predict WHEN a specific nucleus will decay (it's completely random!), but you can predict how many from a large sample will decay. This is radioactivity — discovered accidentally by Henri Becquerel in 1896 when uranium fogged his photographic plates!

Keep building this topic

Read this section alongside the surrounding pages in Radioactive Decay. That gives you the full topic sequence instead of a single isolated revision point.

The Three Types of RadiationPenetrating Power of the Three RadiationsWhat Happens in Each Decay

Practice Questions for Radioactive Decay

An alpha particle consists of which particles?

  • A. 2 protons and 2 neutrons
  • B. 1 proton and 1 neutron
  • C. An electron and a positron
  • D. A proton and an electron
1 markfoundation

Explain why alpha radiation is described as highly ionising but weakly penetrating.

2 marksstandard

Quick Recall Flashcards

Beta particle is?
Fast electron from nucleus
Alpha particle is?
2p + 2n (helium nucleus)

15 questions on Radioactive Decay — practise free

Instant marking, adaptive difficulty, and 6 spaced repetition flashcards. Free until your GCSEs.

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The Three Types of Radiation