Stable and unstable nuclei
Nuclei with too many, or too few, neutrons do exist naturally but are unstable and will disintegrate (or decay) by emitting radiation.
This is called radioactive decay.
It is important to realise that radioactive nuclei disintegrate:
- spontaneously;
- and randomly.
This means that the process of radioactive decay can not be speeded up, slowed down or influenced by artificial means (spontaneous decay).
It also means that we cannot tell when a particular unstable nucleus will decay (random decay).
Key points
- Some nuclei are unstable.
- They disintegrate, emitting radiation randomly, and spontaneously.
- Such nuclei are said to be radioactive.
- Radioactive decay occurs when an unstable nucleus becomes more stable by emitting radiation.