disintegration of a nucleus that occurs spontaneously or as a result of electron capture. One or more different nuclei are formed and usually particles and gamma rays are emitted Sometimes shortened to decay Also called disintegration
The spontaneous transformation of an unstable atomic nucleus into a lighter one, in which radiation is released in the form of alpha particles, beta particles, gamma rays, and other particles. The rate of decay of radioactive substances such as carbon 14 or uranium is measured in terms of their half-life. See also decay, radioisotope.
noun 1. a motor-vehicle tire in which the plies or cords run from one bead to the other at right angles to both beads.
noun, Biology. 1. a basic body plan in which the organism can be divided into similar halves by passing a plane at any angle along a central axis, characteristic of sessile and bottom-dwelling animals, as the sea anemone and starfish. noun 1. a type of structure of an organism or part of an organism in […]
- Radioactive isotope
radioactive isotope n. An isotope having an unstable nucleus that decomposes spontaneously by emission of a nuclear electron or helium nucleus and radiation, thus achieving a stable nuclear composition.
noun, Physics, Chemistry. 1. a succession of elements initiated in the radioactive decay of a parent, as thorium or uranium, each of which decays into the next until a stable element, usually lead, is produced. noun 1. (physics) a series of nuclides each of which undergoes radioactive decay into the next member of the series, […]