BRAINCAKEAlpha Radiation
An alpha particle is a helium nucleus, made of 2 protons and 2 neutrons. It has a charge of +2e and a nucleon number of 4.
Alpha emission happens in large unstable nuclei, such as uranium-238 and radium-226. The strong nuclear force only acts over about 3 fm, while the electrostatic repulsion between protons acts across the whole nucleus. Ejecting a tightly bound group of four nucleons is an energetically favourable way for such a nucleus to become more stable.
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Key terms in this lesson
- Nucleon
- A neutron or a proton; either type of particle found in the nucleus of an atom.
More in Particles and Radiation
- Specific Charge
- The Strong Nuclear Force
- Forces in the Nucleus
- Radioactive Decay
- Beta Radiation
- Gamma Radiation and Electromagnetic Waves
- The Electron Volt
- Photons
All 22 lessons in Particles and Radiation · All AQA AS-level Physics topics