Astatine
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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 element
Glow from a sample of astatine
Emilio Segrè, one of the discoverers of the main-group element astatine
The bismuth target after irradiation contains minuscule quantities of astatine-211.
Polonium
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Polonium is a chemical element; it has symbol Po and atomic number 84. A rare and highly radioactive metal with no stable isotopes, polonium is a chalcogen and chemically similar to selenium and tellu
Astatine
…Astatine is an extremely radioactive element; all its isotopes have half-lives of 8.1 hours or less, decaying into other astatine isotopes, bismuth, polonium, or radon. Most of its isotopes are very unstable, with half-lives of seconds or less. Of the first 101 elements in the periodic table, only francium…
Polonium on brass sheet
The alpha form of solid polonium