78. Alpha, Beta & Gamma Radiation

GCSE Physics: Alpha, Beta & Gamma Radiation

Radioactive decay occurs when unstable isotopes emit radiation to become more stable. There are four main types of nuclear radiation.

1. Alpha Radiation (\alpha)

• Composition: 2 protons and 2 neutrons (identical to a helium nucleus).

• Charge: +2.

• Ionizing Power: Strongly ionizing because of their large size and charge; they easily knock electrons off atoms.

• Penetrating Power: Very low. They only travel a few centimeters in air and are stopped by a single sheet of paper.

2. Beta Radiation (\beta )

• Composition: A high-speed electron.

• Origin: A neutron in the nucleus decays into a proton and an electron. The proton stays, and the electron is emitted.

• Charge: -1.

• Ionizing Power: Moderately ionizing.

• Penetrating Power: Moderate. They can travel several meters in air and are stopped by about 5 mm of aluminium.

3. Gamma Radiation (\gamma )

• Composition: High-energy electromagnetic waves (not particles).

• Origin: Often emitted after alpha or beta decay to release excess energy from the nucleus.

• Charge/Mass: None.

• Ionizing Power: Weakly ionizing because they tend to pass through atoms rather than colliding with them.

• Penetrating Power: Very high. They travel long distances in air and require thick lead or several meters of concrete to be stopped.

4. Neutron Emission (n)

• Composition: A single neutron.

• Origin: Emitted if a nucleus contains too many neutrons, making it unstable.

5. Summary Table