According to Chemicool, the element astatine was first produced by Dale R. Coson, Kenneth Ross Mackenzie and Emilio Segrè in 1940. Berta Karlik and Traude Bernert found astatine in nature three years later, according to Chemicool.
Web Elements explains that scientists can produce astatine by bombarding bismuth-209 with alpha particles. Astatine's symbol is "At," its atomic weight is 210 and its atomic number is 85. Astatine-210 is the longest-lived isotope with a half-life of 8.3 hours, according to Web Elements.
Per Chemicool, astatine-211 is useful as a radioactive tracer and in some cancer treatments. It is a radioactive halogen and accumulates in the thyroid in a manner similar to iodine.