Pearson Edexcel · GCSE · Physics
Course version: 1PH0 · Version from Sept 2016
Recall that alpha, β– (beta minus), β+ (positron) and gamma rays are…
Full specification wording
Topic 6 – Radioactivity: 6.11 Recall that alpha, β– (beta minus), β+ (positron) and gamma rays are ionising radiations
Ionising radiation is radiation that carries enough energy to remove electrons from atoms, turning them into ions.
Checked against the Pearson Edexcel 1PH0 specification (opens in a new tab) on .
- Point 11 of 42
Study notes
From the checked teaching notes for this specification point.
The idea
Ionising radiation is radiation that carries enough energy to remove electrons from atoms, turning them into ions. This specification statement asks you to recall that four named emissions from unstable nuclei are ionising: alpha particles, beta minus particles, beta plus (positron) particles and gamma rays. Alpha particles are helium nuclei (2 protons and 2 neutrons, charge 2⁺) and are strongly ionising but travel only a few centimetres in air. Beta minus particles are fast electrons (charge 1⁻); beta plus particles are positrons (charge 1⁺). Gamma rays are high-frequency electromagnetic waves with no charge. All four can ionise matter, though they differ in how strongly they ionise and how far they penetrate.
What earns the marks
- Identifies alpha particles as ionising radiation emitted from unstable nuclei.
- Recognises beta minus particles as ionising radiation and as fast electrons.
- Recognises beta plus (positron) particles as ionising radiation with a positive charge.
- States that gamma rays are ionising electromagnetic radiation with no charge.
Common mistakes and how to put them right
Treats gamma rays as non-ionising because they have no charge.
Put it right by recalling that gamma rays are highly energetic and do ionise matter.
Confuses beta plus with beta minus.
Put it right by recalling that beta plus is a positron (charge 1⁺) while beta minus is an electron (charge 1⁻).
Assumes only alpha radiation is ionising.
Put it right by recalling that all four named radiations are ionising.
Exam tips
- Learn the four named radiations as a set so a multiple-choice option listing them is recognised quickly.
- Link each radiation to its particle or wave nature and charge to rule out wrong options.
- Remember that ionising means removing electrons from atoms, not simply being radioactive.
Try the lesson
The start of the Topic 6 – Radioactivity: 6.11 Recall that alpha, β– (beta minus), β+ (positron) and gamma rays are ionising radiations lesson, made from checked teaching notes for this specification point.
Have a go first
Which of the following is an ionising radiation?
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