radioisotope

Naturally occurring or synthetic radioactive form of an element. Most radioisotopes are made by bombarding a stable element with neutrons in the core of a nuclear reactor (see fission). The radiations given off by radioisotopes are easy to detect (hence their use as tracers), can in some instances penetrate substantial thicknesses of materials, and have profound effects (such as genetic mutation) on living matter.

Most natural isotopes of relative atomic mass less than 208 are not radioactive. Those from 210 and up are all radioactive.

Uses
Radioisotopes have many uses in medicine, for example in radiotherapy and radioisotope scanning. The use of radioactive isotopes in the diagnosis, investigation, and treatment of disease is called nuclear medicine.

Radioisotope decay
The nucleus of a radioisotope is unstable and undergoes changes by breaking down into a more stable form. A radioisotope decays over a period of time into a new element. As it decays it emits radiation energy in the form of alpha and beta particles and gamma radiation. The time taken for half of the original atoms to decay is known as the half-life. The product of the radioactive decay is called a ‘daughter’ atom.