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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 ...
In 1939, Emilio Segrè suggested that the cyclotron could be used to bombard bismuth (element 83) with alpha particles to produce the then-unknown element 85. Corson, Kenneth Ross MacKenzie, and Segrè discovered and isolated the element in 1940. They named it "astatine" in 1947. [2]
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]
The discovery of tennessine was officially announced in Dubna, Russia, by a Russian–American collaboration in April 2010, which makes it the most recently discovered element as of 2024. One of its daughter isotopes was created directly in 2011, partially confirming the results of the experiment. The experiment itself was repeated successfully ...
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.
It was the third transuranium element to be discovered even though it is the fourth in the series – the lighter element americium was still unknown. [ 7 ] [ 8 ] The sample was prepared as follows: first plutonium nitrate solution was coated on a platinum foil of ~0.5 cm 2 area, the solution was evaporated and the residue was converted into ...