Some naturally occurring isotopes are unstable and spontaneously emit alpha or beta radiation in order to gain stability. This is often accompanied by the emission of gamma-rays.The isotope is converted into a different isotope of another chemical element which may, depending on its number of neutrons and protons, be either radioactive or not.If an atom is unstable the nucleus has an excess of internal energy or an excess of either neutrons or protons. A radioactive atom will attempt to reach stability by ejecting nucleons or by releasing energy in other forms.
Radioactive Decay
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Specification: AQA Physics (7407), AS-level, 3.2.1.2 Stable and unstable nuclei. Topic: Particles and Radiation.
Key terms in this lesson
- Strong nuclear force
- The short-range attractive force between nucleons that overcomes the electrostatic repulsion between protons and holds the nucleus together, becoming repulsive at very short separations.
- Weak nuclear force
- The fundamental interaction responsible for beta decay, in which particles interact through the exchange of W bosons.
- Quark
- A fundamental particle that combines with other quarks to make up hadrons; at A-level, up, down and strange quarks are considered.
- Muon
- A negatively charged lepton, similar to but much heavier than the electron, produced for example by cosmic rays in the atmosphere.
- Neutrino
- An uncharged, almost massless lepton that interacts only very weakly with matter and is emitted, along with a beta particle, in beta decay.
More in Particles and Radiation
- Isotopes
- Specific Charge
- The Strong Nuclear Force
- Forces in the Nucleus
- Alpha Radiation
- Beta Radiation
- Gamma Radiation and Electromagnetic Waves
- The Electron Volt
All 22 lessons in Particles and Radiation · All AQA AS-level Physics topics