| English | Radioactivity |
|---|---|
| Bahasa Melayu | Keradioaktifan |
| 中文 | 放射性 |
Definition
The spontaneous emission of radiation (alpha, beta or gamma) from the unstable nuclei of certain atoms.
In exam terms
Radioactivity is the spontaneous emission of radiation (alpha, beta or gamma) from the unstable nuclei of certain atoms. It is spontaneous because it happens on its own without any external trigger, and it is random because it cannot be predicted exactly when a particular nucleus will decay.
The activity of a source is measured in becquerel (Bq), where 1 Bq = 1 decay per second.
A correct sentence: "Radioactivity is emitted because the nucleus has too many neutrons or protons to be stable." It is not affected by temperature, pressure or chemical state.
Do not confuse it with…
Do not confuse radioactivity with radioactive decay. Radioactivity is the general phenomenon of emitting radiation; radioactive decay is the individual process by which one unstable nucleus changes into a more stable one.
Also distinguish it from ordinary ionisation: radioactivity comes from the nucleus, not from removing electrons.
In Paper 2 you may be asked to define radioactivity, state that it is spontaneous and random, or explain why it is not affected by physical conditions.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)