See also: Dating; Isotope
Spontaneous disintegration or decay of the nucleus of an Atom by emission of particles, usually accompanied by Electromagnetic Radiation. Natural radioactivity is exhibited by several elements, including RADIUM
and Uranium. The Radiation produced is of three types: the Alpha Particle, which is a nucleus (two Protons and two Neutron) of an ordinary Helium atom; the Beta Particle, which is a high-speed electron or, in some cases, a positron (the electron's Antiparticle); and gamma radiation, which is a type of electromagnetic radiation with very
short wavelengths (Gamma Radiation is the most energetic form of
electromagnetic radiation, with a very short wavelength of less than 10^-10 m. Gamma rays
are essentially very energetic X-Ray emitted by excited nuclei. They often accompany alpha or beta particles,
because a nucleus emitting those particles may be left in an excited (higher-Energy) state. Gamma-ray sources are used in medicine to treat cancer, for
diagnostic purposes, and to sterilize equipment and supplies, in industry in the
inspection of castings and welds, and in food processing to kill microorganisms and
retard spoilage.). The rate of disintegration of a radioactive substance is
commonly designated by its half-life, which is the Time required for one half of a given quantity of the substance to decay.
Radioactivity may be induced in stable elements by bombardment with particles of high
energy.