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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.
Emilio Gino Segrè (Italian:; 1 February 1905 – 22 April 1989) [1] was an Italian and naturalized-American physicist and Nobel laureate, who discovered the elements technetium and astatine, and the antiproton, a subatomic antiparticle, for which he was awarded the Nobel Prize in Physics in 1959 along with Owen Chamberlain.
While working with Ernst Foyn she published a paper on the radioactivity of seawater. She discovered that the chemical element 85 astatine is a product of the natural decay processes. The element was first synthesized in 1940 by Dale R. Corson, K. R. MacKenzie, and Emilio Segrè, after several scientists in vain searched for it in radioactive ...
Francium was the last element to be discovered in nature, rather than synthesized in the lab, although four of the "synthetic" elements that were discovered later (plutonium, neptunium, astatine, and promethium) were eventually found in trace amounts in nature as well. [178]
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 ...
Astatine (At) 85 ἄστατος (astatos) Greek "unstable" From Greek ἄστατος (astatos), meaning "unstable". · Former name alabamine (Ab) was an earlier proposed name for astatine Radon (Rn) 86 radium: Latin via German and English [57] Contraction of radium emanation, since the element appears in the radioactive decay of radium.
The synthetic elements are those with atomic numbers 95–118, as shown in purple on the accompanying periodic table: [1] these 24 elements were first created between 1944 and 2010. The mechanism for the creation of a synthetic element is to force additional protons into the nucleus of an element with an atomic number lower than 95.
This is an accepted version of this page This is the latest accepted revision, reviewed on 9 January 2025. This article is about the chemical element. For other uses, see Iodine (disambiguation). Chemical element with atomic number 53 (I) Iodine, 53 I Iodine Pronunciation / ˈ aɪ ə d aɪ n, - d ɪ n, - d iː n / (EYE -ə-dyne, -din, -deen) Appearance lustrous metallic gray solid, black ...