Ionisation (Edexcel GCSE Physics Combined Science): Revision Notes

Ionisation

• The more ionising the radiation, the more dangerous it can be because it causes greater damage to the atoms it hits.

How Dangerous is Ionising Radiation?

1. Ionising radiation can cause serious damage because it alters the structure of atoms and molecules.
2. When radiation ionises atoms in living cells, it can damage DNA, which might lead to mutations or even cancer.
3. The more ionising the radiation, the more dangerous it is to living organisms.

Types of Ionising Radiation

4. Alpha Radiation (α): Alpha particles are big and heavy compared to other forms of radiation.

• This makes them highly ionising because they collide with many atoms along their path, knocking off electrons. However, they can't travel far and are easily stopped by things like paper or skin.

5. Beta Radiation (β): Beta particles are smaller and faster than alpha particles.

• They are less ionising because they collide with fewer atoms, but they can still penetrate materials better than alpha particles (they can pass through paper but are stopped by thin metals like aluminium).

6. Gamma Radiation (γ): Gamma rays are neutral (they have no charge) and are electromagnetic waves, not particles.

• They are the least ionising because they don't interact as easily with atoms, but they are the most penetrating and require thick lead or concrete to stop them.