a rare element of the halogen family. Symbol: At; atomic number: 85.
a radioactive element of the halogen series: a decay product of uranium and thorium that occurs naturally in minute amounts and is artificially produced by bombarding bismuth with alpha particles. Symbol: At; atomic no: 85; half-life of most stable isotope, 210At: 8.1 hours; probable valency: 1,3,5, or 7; melting pt: 302°C; boiling pt: 337°C (est)

radioactive element, named 1947, from Greek astatos “unstable” (see astatic) + chemical suffix -ine (2). So called for its short half-life and lack of stable isotopes. “The element appears not to have a stable form and probably does not exist in nature” [Flood, “Origin of Chemical Names”].

astatine as·ta·tine (ās’tə-tēn’, -tĭn)
Symbol At
A radioactive halogen element. Its longest lived isotope has a mass number of 210 and a half-life of 8.1 hours. Atomic number 85; melting point 302°C; boiling point 337°C; valence probably 1, 3, 5, 7.
Symbol At
A highly unstable, rare, radioactive element that is the heaviest of the halogen elements. Its most stable isotope has a half-life of 8.3 hours. Atomic number 85; melting point 302°C; boiling point 337°C; valence probably 1, 3, 5, 7. See Periodic Table.


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