Topic 3 – Radioactivity

Radioactivity Definition

Radioactivity is the spontaneous emission of radiation from an unstable atomic nucleus

Unstable Nucleus

An unstable nucleus has an imbalance of protons and neutrons or excess energy

Types of Radiation

The three types of nuclear radiation are alpha beta and gamma

Alpha Radiation

Alpha radiation consists of two protons and two neutrons

Alpha Ionisation

Alpha radiation is strongly ionising because it has a large mass and charge

Alpha Penetration

Alpha radiation has a short range and is stopped by paper or skin

Beta Radiation

Beta radiation is a fast moving electron emitted from the nucleus

Beta Ionisation

Beta radiation is moderately ionising

Beta Penetration

Beta radiation can pass through paper but is stopped by thin aluminium

Gamma Radiation

Gamma radiation is electromagnetic radiation emitted from the nucleus

Gamma Ionisation

Gamma radiation is weakly ionising

Gamma Penetration

Gamma radiation is very penetrating and requires thick lead or concrete to stop it

Ionising Radiation Effect

Ionising radiation removes electrons from atoms

Biological Damage

Ionisation can damage cells and DNA and increase the risk of cancer

Half Life Definition

Half life is the time taken for the activity or number of unstable nuclei to halve

Uses of Radiation

Radiation is used in medicine industry smoke alarms and sterilisation