PhysicsChapter 12: Nuclear Physics
Radioactivity
Introduction
Radioactivity is the spontaneous and random emission of radiation from an unstable atomic nucleus. An unstable nucleus changes into a more stable state by emitting nuclear radiation. The main types studied at this level are: alpha (α) beta (β) gamma (γ)
Definition
Spontaneous
Radioactive decay happens naturally without needing an external trigger.
Random
It is impossible to predict exactly when a particular unstable nucleus will decay. However, for a very large number of nuclei, the overall behaviour can be described statistically.
Nuclear Change
Radioactivity involves changes in the nucleus, not ordinary chemical changes in electron arrangement.
Activity
The activity of a radioactive sample tells how many nuclear decays occur per second. The SI unit is: **becquerel (Bq) 1 Bq = 1 decay per second**
Background Radiation
People are naturally exposed to small amounts of radiation from sources such as: rocks and soil; cosmic radiation; some materials in the environment; medical procedures when used.
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Radioactivity
Sticky Notes · Quick Revision
RADIOACTIVITY
- Unstable nucleus
DECAY
- Spontaneous + random
ACTIVITY
- Bq
60-second revision
- Radioactivity → spontaneous + random nuclear decay.
- Activity → decays per second.
- Unit → Bq.
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