Radioactivity is the process in which unstable atomic nuclei become more stable by spontaneously emitting highly energetic particles and/or energy. A sample of material is said to be radioactive if some of its atomic nuclei are emitting such radiation....

Radioactivity is the process in which unstable atomic nuclei become more stable by spontaneously emitting highly energetic particles and/or energy. A sample of material is said to be radioactive if some of its atomic nuclei are emitting such radiation....

Radioactivity originates from extraterrestrial sources and terrestrial geologic sources. All elements with more than 83 protons (i.e., an atomic number greater than 83) are radioactive. Some radioactive isotopes also occur in elements with lower atomic...

In 1896, the French physicist Henri Becquerel accidentally found that an ore of uranium, pitchblende, emits an invisible form of radiation, somewhat similar to light. The phenomenon was soon given the name radioactivity and materials like pitchblende...

Radioactivity is defined as the process by which atoms emit particles and high energy rays from their nuclei. Although most elements can be rendered radioactive, the process occurs naturally in only a very few. The modern understanding of radioactivity...

The nucleus of each atom has a specific number of protons and neutrons and is either stable or unstable, depending on the relative number of each. The most stable atoms are those that have an equal number of protons and neutrons. Atoms that are...

Radioactive decay is the process in which an atom emits another particle or particles. A radioactive element exhibits fewer decays per unit of time at an exponential rate. The half-life is how long it takes the element to decay to half its original...

Property exhibited by certain types of matter of emitting radiation spontaneously. The phenomenon was first reported in 1896 by Henri Becquerel for a uranium salt, and it was soon found that all uranium compounds are radioactive due to the uranium's...

Radioactive decay is the process by which an atomic nucleus undergoes a spontaneous change, emitting an alpha particle or beta particle and/or a gamma ray. Radioactive decay is a natural process that takes place in the air, water, and soil at all...

The phenomenon exhibited on the spontaneous disintegration of the atoms of certain elements whereby they emit IONISING RADIATION in the process. The radiation is emitted variously in three ways, being as alpha particles (comprising two protons plus two...

Spontaneous disintegration of an element. The heaviest elements emit radiation of short wavelength (gamma rays), fast electrons (beta rays) and helium particles (alpha...

Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. This decay, or loss of energy, results in an atom of one type, called the parent nuclide...