![]() ![]() ![]() Reactions of astatine in the vapour state with chlorine, bromine, and iodine have produced the diatomic compounds AtCl, AtBr, and AtI. IsotopesĬurrently, there are 39 known radioactive isotopes of astatine ranging from mass number 191 to 229 with the maximum half-life reaching 8.1 hours for _. Corson, Kenneth Ross MacKenzie, and Emilio Segrè in which they suggested the name “astatine,” derived from a Greek word “astatos” for unstable for the element 85. In early 1947, Nature (a British Weekly Scientific Journal) published a letter signed by Dale R. Moreover, the confirmation of astatine took three more years after the announcement of its discovery. They bombarded bismuth-209 with alpha particles in a cyclotron (particle accelerator) and saw several forms of radiation including the emission of α, γ, and X-rays, and also low energy electrons, all having a half-life of about 7.5 hours. Corson, Kenneth Ross MacKenzie, and Emilio Segrè took a different approach rather than looking for eka-iodine in nature. Later in 1940, at the University of California, Berkeley, three scientists named Dale R. However, his claims also met the same fate once he was unable to reproduce his results.Įmilio Segrè, one of the discoverers of the main-group element astatine He announced the discovery of element 85 as the beta decay product of radium A (polonium-218) and chose the name “helvetium” as in Helvetia, the Latin for Switzerland. Another unsuccessful assertion to isolate astatine came about in 1940 by a Swiss chemist, Walter Minder. Nevertheless, their claims were rejected by the Austrian chemist Fredrich Paneth due to the lack of substantial standards to enable identification. By the end of the 1930s, Horia Hulubei and Yvette Cauchois claimed to have discovered X-ray wavelengths for three spectral lines of eka-iodine in the emission spectra of radon. Several unsuccessful claims were reported during the 1920s and 1930s by scientists from several countries including the UK, Germany, British India, Denmark, France, and Switzerland. However, his claims were disproved later as his methods could not replicate the results, and the equipment was found to be faulty. He suggested the name Alabamine to honor the state where the work was done. The first claim about the discovery of Astatine was made around the year 1931 when Fred Allison, along with his associates, attempted to discover eka-iodine at the Alabama Polytechnic Institute. The search for Astatine goes back to the year 1922, and it includes a fascinating history in regards to its discovery, confirmation, and naming. After establishing the physical basis of the classification of chemical elements, Neil Bohr suggested the name “eka-iodine” for element no. Mendeleev used the prefixes “eka-, dvi- or dwi-, and tri-,” taken from the Sanskrit names of digits 1, 2, and 3, depending upon whether the predicted element was one, two, or three places down from the known elements of the same group in his table. The periodic table published by Russian chemist Dmitri Mendeleev in 1869, suggested the first prediction of Astatine.
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