The first creation of the element was in 1940 by Dale R. Corson, Kenneth Ross MacKenzie, and Emilio G. Segrè at the University of California, Berkeley, who named it from the Greekestates (ἄστατος), meaning "unstable".[1]
Astatine is highly radioactive and all itsisotopes have half-lives of approximately 8 hours or less, the longest being astatine-210 with a half-life of a bit over eight hours.[2] Some of itsisotopes may be found in nature, but because it is sounstable, only about anounce exists in theEarth's crust at any point in time. Chemists say it is the rarest element in the Earth's crust. Less reactive thaniodine, astatine is the least reactive of the halogens. Only a few compounds with metals have been found, in the form of astatides ofsodium,palladium,silver,thallium, andlead.
