My Science School

Actinium is a radioactive element. It was discovered by Andre Debierne in 1899 in Paris. He worked with Marie Curie and discovered actinium in pitchblende (a uranium ore). It was the same ore from which radium and polonium had already been extracted. He was able to identify this new element because the kind of radioactive emissions from his sample was not explainable by the presence of any known element. Although Debierne was able to discover the element, he was unable to isolate pure actinium. The high radioactivity level of actinium makes it very useful in producing neutrons.

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In Dmitri Mendeleev’s periodic table of the year 1869, there was a space directly under iodine. The name for the element to fill this space was called ‘eka-iodine’ and the scientists began searching for the element that would fill up this space. But even 71 years later, this element could not be discovered in nature and was instead synthesized in the earliest particle accelerator.

Astatine was first produced by Dale R. Coson, Kenneth Ross Mackenzie, and Emilio Segrè at the University of California, Berkeley in 1940. Segrè, who was working with Carlo Perrier, had synthesized technetium in the year 1937. Researchers had found that the isotope they had created was radioactive, so they named this element based on the Greek term ‘astatos’ which means unstable.

Traces of astatine appear in uranium and thorium minerals as a decay product naturally. The element is highly radioactive. Astatine is the rarest naturally occurring element and at any given time, there are only about 25 grams of naturally occurring astatine on our planet.

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