Image of a person’s skeleton obtained using an excited
Technetium is an unusual radioactive element. Although a d-transition element (under manganese in Group VIIB) with a small atomic number (Z 43), it has no stable isotopes. The nucleus of every technetium isotope is radioactive and decays, or disintegrates, to give an isotope of another element. Many of the technetium isotopes decay by emitting an electron from the nucleus.
Because of its nuclear instability, technetium is not found naturally on earth. Nevertheless, it is produced commercially in kilogram quantities from other elements by nuclear reactions, processes in which nuclei are transformed into different nuclei.
Technetium (from the Greek tekhnetos, meaning “artificial”) was the first new element produced in the laboratory from another element. It was discovered in 1937 by Carlo Perrier and Emilio Segrè when the element molybdenum was bombarded with deuterons (nuclei of hydrogen, each having one proton and one neutron). Later, technetium was found to be a product of the fission, or splitting, of uranium nuclei. Technetium is produced in nuclear fission reactors used to generate electricity.
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Technetium is one of the principal isotopes used in medical diagnostics based on radioactivity. A compound of technetium is injected into a vein, where it concentrates in certain body organs. The energy emitted by technetium nuclei is detected by special equipment and gives an image of these body organs. The figure below shows the image of a person’s skeleton obtained from technetium administered in this manner. The technetium is eliminated by the body after several hours.