Astatine, element 85, was first produced in 1940 by Dale Corson, Kenneth MacKenzie, and Emilio Segrè in the cyclotron at the University of California, Berkeley. Several years later, it was discovered in nature. It is named for its short half-life, as explained by Carson in the 4 January 1947 issue of Nature:

We propose to call element 85 “astatine” from the Greek αστατος, unstable. Astatine is in fact the only halogen without stable isotopes.

There were several earlier claims for discovery that were later disproven, but the names from those mistaken finds can sometimes be found in older chemical literature. One group at the Alabama Polytechnic Institute (now Auburn University) dubbed the element alabamine, and a British-Swiss team dubbed it anglo-helvetium.1

The chemical symbol for astatine is At. (Arsenic is As.)

1Oxford English Dictionary, astatine, 2nd Edition, 1989, Oxford University Press, accessed 11 November 2009,

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