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Radioactivity
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Radioactivity is the emission of radiation by the nucleus of an atom. This radiation can be in the form of alpha particles (helium nuclei), beta particles (electrons or positrons), or gamma rays (high-energy photons). Radioactivity is a spontaneous process that occurs when the nucleus of an atom is unstable. The instability can be due to an excess of protons or neutrons in the nucleus, or to a combination of both. Alpha particles and beta particles are emitted when the nucleus is trying to achieve a more stable ratio of protons to neutrons. Gamma rays are emitted when the nucleus is trying to achieve a lower energy state.
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