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Astatine is a chemical element; it has symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements. All of astatine's isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours.
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Representative lifetimes of stars as a function of their masses The change in size with time of a Sun-like star Artist's depiction of the life cycle of a Sun-like star, starting as a main-sequence star at lower left then expanding through the subgiant and giant phases, until its outer envelope is expelled to form a planetary nebula at upper right Chart of stellar evolution
Structure of astatine monoiodide, one of the astatine interhalogens and the heaviest known diatomic interhalogen. Astatine is known to react with its lighter homologs iodine, bromine, and chlorine in the vapor state; these reactions produce diatomic interhalogen compounds with formulas AtI, AtBr, and AtCl. [4]
Astatine-212 and astatine-216 are expected to decay either way. The most stable isotope of astatine is astatine-210, which has a half-life of about 8.1 hours. This isotope's primary decay mode is positron emission to the relatively long-lived alpha emitter, polonium-210. In total, only five isotopes of astatine have half-lives exceeding one ...
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Only a Trillion is a collection of ten science essays and three scientific spoof articles by Isaac Asimov.It was the first collection of science essays published by Asimov
Organoastatine chemistry describes the synthesis and properties of organoastatine compounds, chemical compounds containing a carbon to astatine chemical bond. Astatine is extremely radioactive, with the longest-lived isotope (210 At) having a half-life of only 8.1 hours. Consequently, organoastatine chemistry can only be studied by tracer ...