What Are Radioactive Isotopes?

Radioactive isotopes, also called radioisotopes, are atoms with a different number of neutrons than a usual atom, with an unstable nucleus that decays, emitting alpha, beta and gamma rays until the isotope reaches stability. Once it's stable, the isotope becomes another element entirely. Radioactive decay is spontaneous so it's often hard to know when it will take place or what sort of rays it will emit during decay.

How Many?

There are around 3800 radioactive isotopes. At present there are up to 200 radioactive isotopes used on a regular basis, and while some are found in nature, most others have to be manufactured to suit specific needs, such as for hospitals, research labs and manufacturers.

How Are They Manufactured?

Radioactive isotopes can be manufactured in several ways, the most common by neutron activation in a nuclear reactor which involves capturing a neutron by the nucleus of an atom which results in an excess of neutrons (neutron rich). Some radioactive isotopes are produced in a cyclotron in which protons are introduced to a nucleus resulting in a deficiency of neutrons (proton rich). (source:http://www.eoearth.org/article/Radioisotopes_in_industry)

Significance

Radioactive isotopes have very useful properties. Alpha, beta and gamma radiation can permeate solid objects like an x-ray, but are progressively absorbed by them. The amount of this penetration depends on several factors including the energy of the radiation, mass of the particle, and density of the solid. These properties can lead to many uses for radioisotopes in the scientific, medical, archaeological and industrial fields.The uses of radioactive isotopes in these fields depend on what element they become after they reach stability.

Uses in the Medical Field

Chromium-51, for example, which forms from emitted alpha rays during radioactive isotope decay, is used in the classifying of blood cells and measuring protein loss in the human body. Cobalt-60, another element formed from radioactive isotopes emitting beta and gamma rays, is often used in cancer treatment. Oxygen-18 and Technetium-99 are used as biological tracers, helping doctors locate tumors and other problems in various parts of the human body. They are also used in x-rays and bone imaging.They are used in killing off damaged cells and treating abnormal cell growth as rapidly dividing cells are particularly sensitive to radiation.

Uses in Archaeology and Industry

They can also be used in the field of archaeology. Radioactive isotope elements such as Carbon-14, Lead-210, and Potassium-40 are used in dating of rocks and historical earth. Chlorine-36 and Tritium are used in measuring the age of ground water up to millions of years. In industry they are used as fuel for nuclear reactors, in the manufacturing of domestic smoke alarms, tracing factory waste that may cause pollution, and predicting the behavior of heavy metals in water. Sodium-24 and Magnesium-27, for example, are used to locate leaks in water pipes, while iridium-192 is used in wire in radiography devices.

Other Uses

Other uses of these isotopes are in the study of chemical and biological processes in plant life for agriculture, treating and preserving food in order to make it safer for consumption and to have a longer shelf-life when in stores for purchase, and for chemical pest control