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Radioactivity

G3 Physics and O-Level Physics radioactivity hub: atoms & isotopes, nuclide notation, alpha/beta/gamma decay, half-life, detectors, hazards, and fission/fusion revision links.

  • G3 Pure Physics K323 / retained O-Level Physics 6091
  • 8 lessons
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Before you begin

Follow the lesson route in order when the topic is new. If you are revising, begin with the topic check and return to the lesson it identifies.

How the ideas connect

  1. Atomic nucleus
  2. Ionising radiation
  3. Random decay
  4. Applications and risk

Learn in order

Lesson route

01

Foundations

  1. 01Atoms and isotopesLocate protons, neutrons and electrons, then use proton and nucleon numbers to identify isotopes.
  2. 02Nuclide notationInterpret $^A_ZX$, calculate neutron number, and balance radioactive-emission equations.
02

Decay and radiation

  1. 03Radioactive decayExplain random and spontaneous decay, balance emissions, and correct for background.
  2. 04Types of emissionCompare alpha, beta-minus and gamma by nature, ionisation and penetration.
  3. 05Half-lifeSolve repeated-halving problems using tables, decay curves and corrected count-rate.
03

Applications and energy

  1. 06Uses and dangersJustify medical and industrial uses and hazards using half-life, penetration and ionisation.
  2. 07Radiation detectorsUse GM readings, absorbers and cloud-chamber tracks as evidence, including background correction.
  3. 08Fission and fusionDistinguish splitting heavy nuclei from joining light nuclei and link both to energy release.

Prove your understanding

Practice and repair

Recommended next stepO Level Radioactivity Hub topic checkFind the exact ideas that need another look.Start topic check

Other ways to practise

Key ideas and reference

Use this concise Radioactivity checklist for orientation. Open a linked lesson for definitions, derivations, diagrams and worked examples.

  • Locate protons, neutrons and electrons, then use proton and nucleon numbers to identify isotopes.
  • Explain random and spontaneous decay, balance emissions, and correct for background.
  • Justify medical and industrial uses and hazards using half-life, penetration and ionisation.
  • Distinguish splitting heavy nuclei from joining light nuclei and link both to energy release.
Course coverage and review details

This route covers: Interpret atomic and nuclide structure and represent radioactive emissions with balanced equations. Compare alpha, beta-minus and gamma, account for background, and solve half-life problems. Evaluate radiation uses and hazards and distinguish fission from fusion.

G3 Pure Physics and retained O-Level access share this learner route while qualification-specific evidence remains separate.

Reviewed Jul 19, 2026

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Frequently asked questions

Who is this radioactivity hub for?

This hub is for O Level students preparing for decay equations, half-life calculation, and radiation application/safety explanations.

What should I revise before this chapter?

Revise atom structure, SI units, and energy-store language first so nuclide and decay questions are easier to interpret.

What mistakes lose marks in radioactivity questions?

Most losses are from not subtracting background count-rate, wrong proton-number change in beta decay, and misusing half-life fractions.

What should I do after this hub?

Complete radioactivity quiz + structured practice, then run mixed O Level revision from the main portal.