Radioactive isotopes

Abbreviated as RI. Also called radioisotope. An isotope that undergoes radioactive decay. Radioactive isotopes have been artificially created for all elements, and because they have the same chemical properties as stable isotopes, they are used as tracers in the fields of science, engineering, and agriculture. They are also used in medicine and diagnosis, taking advantage of their radioactivity. Large amounts of radioactive isotopes (especially cobalt-60) are used as radiation sources for industrial use of radiation and research into radiation chemistry. Elements that do not have naturally occurring stable isotopes, such as Tc, Pm, and many other actinide elements, only became clear about the properties of the elements after radioactive isotopes were discovered.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

略称RI．ラジオアイソトープともいう．同位体のうちで放射性崩壊をするもの．すべての元素について放射性同位体が人工的につくられており，安定同位体と化学的性質が同じであることを利用して，理学，工学，農学の各分野でトレーサー(追跡子)として利用されている．また，放射能を利用して，医療，診断にも使われる．放射線の工業的利用および放射線化学の研究には，大量の放射性同位体(ことにコバルト60)が放射線源として用いられている．Tc，Pm，そのほか，多くのアクチノイド元素のように，天然に安定同位体が存在しない元素は，放射性同位体が発見されてはじめてその元素の性質が明らかになった．

出典　森北出版「化学辞典（第2版）」化学辞典 第2版について　情報