GCSE Physics - Alpha, Beta and Gamma Radiation #33

Isotopes and Radioactivity

• Isotopes: Different forms of elements that have the same number of protons but different numbers of neutrons.

• Stability of Isotopes: Only one or two of an element’s isotopes are stable. The rest are unstable and can undergo radioactive decay.

• Radioactive Materials: Consist of unstable isotopes that can decay by emitting radiation.

Types of Nuclear Radiation

1. Alpha Radiation

   • Alpha Particles: Composed of two protons and two neutrons; essentially the same as a helium nucleus (represented as He).

   • Charge: Have an overall charge of +2 due to the two protons and no electrons.

   • Penetration:

     • Easily stopped by collisions with other molecules.

     • Can travel a few centimeters in air.

     • Absorbed by a single sheet of paper.

   • Ionization: Very strongly ionizing; can knock electrons off atoms easily.

2. Beta Radiation

   • Beta Particles: Essentially electrons with a charge of -1 and negligible mass.

   • Emission: Emanate when a neutron in an atom decays into a proton and an electron; the proton stays in the nucleus.

   • Penetration:

     • Moderately ionizing.

     • Can travel several meters in air or require about five millimeters of aluminum to stop.

3. Gamma Radiation

   • Gamma Rays: Waves of electromagnetic radiation (unlike alpha and beta particles).

   • Emission: Often released after alpha or beta radiation as the nucleus releases extra energy.

   • Charge and Mass: Massless and uncharged, allowing them to pass through materials.

   • Penetration:

     • Weakly ionizing.

     • Can travel long distances in air.

     • Requires thick sheets of lead or several meters of concrete to stop.

4. Neutron Emission

   • If a nucleus has too many neutrons, it may emit one to restore stability.

Summary of Radiation Types

• Alpha Particles: 2 protons and 2 neutrons; stopped by paper.

• Beta Particles: Electrons; stopped by aluminum.

• Gamma Rays: Electromagnetic waves; stopped by thick lead.