GCSE Chemistry Revision: Radioactive Decay and Nuclear Radiation

5th April 2017

GCSE Science – Physics – Radiation

KEY STAGE 4 – GCSE Physics Revision Guide - The Electromagnetic Spectrum


Then use this Revision Guide on Radiation to remember all the Key Study Points in the GCSE Syllabus and get Full Marks in your GCSE Physics Exam.

What is Radiation?

The emission of energy through space or other materials as:

  • electromagnetic waves

  • moving subatomic particles.

Materials and substances which emit radiation all the time are known as Radioactive materials.

Three types of Nuclear Radiation

  • alpha

  • beta

  • gamma.

As Radiation travels, it can be absorbed by materials or substances which are in its path, causing the intensity to decrease as it travels away from the source.

How the Radiation is absorbed will depend on the type of Radiation AND the type of material it is encounters.

This is because each type of Radiation has its own characteristics:


  • Weakest type of Radiation

  • Travels only a few centimetres  in air

  • Cannot penetrate your hand or  a sheet of paper


  • Stronger than Alpha, but not as strong as Gamma

  • travels much further through air (many centimetres)

  • Can penetrate a piece of paper and your hand

  • Cannot penetrate a thin Aluminium sheet (a few millimetres thick)


  • The strongest type of Radiation

  • Can penetrate paper, your hand and a sheet of Aluminium

  • Can only be stopped by very dense materials:

    • a thick sheet (several centimetres) of Lead,

    • thick concrete walls (several metres)

    • water can also be used to stop Gamma rays.

How do we use Radiation?

  • ALPHA: Smoke detectors

  • BETA: In factories, to test the thickness of materials being produced (e.g. paper or plastic)

  • GAMMA:  hospitals / medical treatments.

Radioactive Decay and Half-Life

The atomic nuclei of radioactive substances are unstable and change or break down into another type of atom, this is known as “Radioactive Decay”.

For example:

Carbon-14 is unstable and decays - emitting Beta radiation

Nitrogen - 14 is produced as a result.

The Half-Life of a radioactive substance is the length of time it takes for half of the nuclei in that substance to decay/be lost as radiation.  


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