Radioactivity involves three types of ionizing radiation: alpha radiation consists of helium nuclei that can be stopped by a few centimeters of air or paper; beta radiation are high-speed electrons that require a layer of aluminum or few meters of air to stop; gamma radiation is very high frequency photons that require several meters of lead or concrete to stop.

1. Radioactivity
Alpha, Beta and Gamma Radiation

2. • All of these are ionising radiation
• Alpha and Beta radiation cause a decay of an
element into another

3. Alpha Radiation
• Two protons and two neutrons (helium nucleus)
• Stopped by a few centimetres of air or paper

4. Beta Radiation
• High speed electrons
• Stopped by a layer of aluminum or few metres
of air

5. Gamma Radiation
• Very high frequency photon
• Stopped by several metres of lead or concrete