radioactivity: Radioactive Emissions

Natural radioactivity is exhibited by several elements, including radium, uranium, and other members of the actinide series, and by some isotopes of lighter elements, such as carbon-14, used in radioactive dating. Radioactivity may also be induced, or created artificially, by bombarding the nuclei of normally stable elements in a particle accelerator. Essentially there is no difference between these two manifestations of radioactivity.

The radiation produced during radioactivity is predominantly of three types, designated as alpha (α), beta (β), and gamma (γ) rays. These types differ in velocity, in the way in which they are affected by a magnetic field, and in their ability to penetrate or pass through matter. Other, less common, types of radioactivity are electron capture (capture of one of the orbiting atomic electrons by the unstable nucleus) and positron emission—both forms of beta decay and both resulting in the change of a proton to a neutron within the nucleus—an internal conversion, in which an excited nucleus transfers energy directly to one of the atom's orbiting electrons and ejects it from the atom.

Sections in this article:

• Introduction
• Discovery of Radioactivity
• Radioactive Disintegration Series
• Half-Life of an Element
• Radioactive Decay
• Gamma Radiation
• Beta Radiation
• Alpha Radiation
• Radioactive Emissions
• Bibliography

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