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Astatine-218 was the first astatine isotope discovered in nature. [113] Astatine-219, with a half-life of 56 seconds, is the longest lived of the naturally occurring isotopes. [6] Isotopes of astatine are sometimes not listed as naturally occurring because of misconceptions [103] that there are no such isotopes, [114] or discrepancies in the ...
Astatine has 23 nuclear isomers (nuclei with one or more nucleons – protons or neutrons – in an excited state). A nuclear isomer may also be called a " meta -state"; this means the system has more internal energy than the " ground state " (the state with the lowest possible internal energy), making the former likely to decay into the latter.
Astatine can replace a hydrogen atom in benzene to form astatobenzene C 6 H 5 At; this may be oxidized to C 6 H 5 AtCl 2 by chlorine. By treating this compound with an alkaline solution of hypochlorite, C 6 H 5 AtO 2 can be produced. [31] Astatine-labelled iodine reagents have been used to synthesise RAt, RAtCl 2, R 2 AtCl, and RAtO 2 (R ...
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Astatine-229 This page was last edited on 23 January 2021, at 05:47 (UTC). Text is available under the Creative Commons Attribution-ShareAlike 4.0 License ...
Porcelain dish, Chinese Qing, 1644–1911, Hard-paste decorated in underglaze cobalt blue V&A Museum no. 491-1931 [1] Victoria and Albert Museum, London. Hard-paste porcelain, sometimes called "true porcelain", is a ceramic material that was originally made from a compound of the feldspathic rock petuntse and kaolin fired at a very high temperature, usually around 1400 °C.
Two-step procedures are used today, first synthesising stable astatoaryl prosthetic groups before incorporating them into the protein. [3] Not only is the C–At bond the weakest of all carbon–halogen bonds (following periodic trends), but also the bond easily breaks as the astatine is oxidised back to free astatine.
This page was last edited on 12 November 2022, at 21:48 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may apply.