Asztatin

Asztatin is a chemical element with the symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, with estimated total amounts in the upper crust of the Earth at any one time being less than 1 gram. Asztatin is a halogen, belonging to the same group as fluorine, chlorine, bromine, and iodine.

All isotopes of asztatin are radioactive. The longest-lived isotope is asztatin-210, with a half-life of 8.1 hours. Due to its extreme rarity and radioactivity, asztatin has no significant commercial applications. Its primary use is in scientific research, particularly in nuclear medicine, where it can be used to target cancer cells.

Asztatin was first synthesized in 1940 by Dale R. Corson, Kenneth Ross MacKenzie, and Emilio Segrè at the University of California, Berkeley, by bombarding bismuth with alpha particles. It was named after the Greek word "astatos," meaning unstable. Chemically, asztatin behaves similarly to iodine, forming compounds with other elements. However, its chemical properties are not as well-studied due to its scarcity.

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