• Question: Why are materials radioactive

    Asked by bhut532rynd94 to Tony G, Ruth A, michaelsullivan, Luke, Hamish, graemesutcliffe, ciarahurley, Caroline, Calum, billlionheart on 2 Apr 2026.
    • Photo: Hamish Cavaye

      Hamish Cavaye answered on 2 Apr 2026:

      All materials are made of atoms. In the centre of an atom is the nucleus, which is made up of protons and (usually) neutrons. Depending on the number of protons and neutrons, the nucleus can be unstable. This means there is a different number of protons and neutrons that is more stable. You can think of the stability like a hill. If you put a ball at the top of a hill, it will roll down that hill until it is “more stable”.

      When the nucleus is unstable, some of the protons and neutrons can fly out of the nucleus, or they can convert from one to the other. This change in the nucleus releases some energy, which we see as radiation.

      So the unstable arrangement of protons and neutrons in an atom’s nucleus are what causes it to be radioactive.

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