Astatine

Astatine (/ˈæstətiːn/ AS-tə-teen or /ˈæstətɪn/ AS-tə-tin) – from the Greek astatos ("unstable") – is a radioactive chemical element with the chemical symbol At and atomic number 85. It occurs on Earth only as the result of the radioactive decay of certain heavier elements. All of its isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours. Accordingly, much less is known about astatine than most other elements. Wh... More

Astatine (/ˈæstətiːn/ AS-tə-teen or /ˈæstətɪn/ AS-tə-tin) – from the Greek astatos ("unstable") – is a radioactive chemical element with the chemical symbol At and atomic number 85. It occurs on Earth only as the result of the radioactive decay of certain heavier elements. All of its isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours. Accordingly, much less is known about astatine than most other elements. What properties are known are consistent with it being a heavier analog of iodine; many other properties have been estimated based on this resemblance. Elemental astatine has never been viewed, because a mass large enough to be viewed by the naked human eye would be immediately vaporized by the heat generated by its own radioactivity. Astatine may be dark, or it may have a metallic appearance and be a semiconductor, or it may even be a metal. It is likely to have a much higher melting point than does iodine, on par with those of bismuth and...

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