LuduminaAT-03 · AT-U2 · Planned
Radioactive decay and nuclear emissions
Learning objectives
Describe unstable-nucleus decay and activity; compare alpha, beta, gamma and neutron emissions, penetration and ionisation.
8463 §§4.4.2.1 / 8464 §§6.4.2.1
DfE single-science pp.43–44 / Combined pp.35–36. Evidence checked 30 September–1 October 2026. Skills: WS1.2,1.5,4.2; MS2c.
Explanation
Radioactive decay is a random change of an unstable nucleus. Activity counts decays per second, whereas a detector counts only what it registers. Alpha, beta, gamma and neutron emissions differ in charge, mass and interactions; beta originates in a nuclear process, not from an ordinary electron-shell transition.
Concepts, equations and units: Activity Bq=decays/s; count rate counts/s differs due to detection; alpha helium nucleus, beta electron from nuclear process, gamma EM, neutron uncharged.
Prediction, demonstration and game exercise
Predict, observe, explain
Use stochastic model decay and shielding cards; distinguish emissions from electron-shell events.
Planned learner game exercise
Select shielding/detection for supplied evidence and classify radiation by charge, mass, range and penetration.
Independent practice
Explain decay randomness and interpret three detector/shield cases.
Original practice example · Shared
A source undergoes 300 decays per second. State activity and unit. Must a detector read 300 counts/s?
Show working and model answer
Working / reasoning
Activity is decays/s; detector efficiency, geometry and background affect measured counts.
Answer
300 Bq; no, count rate need not equal activity.
Exit check and success criteria
Alpha/beta/gamma identities and comparisons correct; neutron identified; activity/count rate distinguished.
During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.
Misconceptions, practical links and mastery
Check these misconceptions
Beta is an orbital electron ejected by warming; gamma is a massive particle; decay can be timed for one nucleus.
Practical preparation
Simulation/supplied detector data; any school source work follows specialist controls; no RP.
Virtual preparation and revision only. Required hands-on activities and school records remain separate.
Proposed mastery
0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.