Some atoms have unstable nuclei because of 'extra' neutrons.

Carbon-14 has an unstable nuclei - it has 6 protons and 8 neutrons i.e. extra
neutrons!

To become more stable, these unstable nuclei throw particles out - this process
is called decay.

Carbon-14 is radioactive. It is a radioisotope and when it decays
it gives out radiation.

All radioisotopes eventually turn into stable atoms by giving out radiation.

Decay is a random process.

Radiation consists of three types of particles:

1. alpha

2. beta

3. gamma

An alpha particle consists of two protons and two neutrons. They can be stopped
with paper, slows down quickly in air.

A beta particle is a fast electron. Can travel 20-30cm in air and through thin
sheets of paper and metal.

A gamma ray is a high-energy ray. Can travel deep into the body, only thick
blocks of concrete or lead can stop it penetrating further.

Radiation can cause cells to mutate - can lead to cancer.

We are surrounded by low-level radiation from rocks and cosmic rays
called background radiation.

Radiation can be useful:

1. Used as tracers

2. To kill germs

3. Cancer treatment

4. Carbon dating - to find the age of once living organisms.

5. Dating rocks.