单词 | tennessine |
释义 | tennessineten·nes·sineT5115450 (tĕn′ə-sēn′)tennessinetennessine(tĕn`əsēn), artificially produced radioactive chemical elementelement,in chemistry, a substance that cannot be decomposed into simpler substances by chemical means. A substance such as a compound can be decomposed into its constituent elements by means of a chemical reaction, but no further simplification can be achieved. ..... Click the link for more information. ; symbol Ts; at. no. 117; mass number of most stable isotopeisotope , in chemistry and physics, one of two or more atoms having the same atomic number but differing in atomic weight and mass number. The concept of isotope was introduced by F. ..... Click the link for more information. 294; m.p., b.p., sp. gr., and valence unknown. Tennessine is a member of Group 17 of the periodic tableperiodic table, chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley. In the periodic table the elements are arranged in columns and rows according to increasing atomic number (see the table entitled ..... Click the link for more information. , the halogenshalogen [Gr.,=salt-bearing], any of the chemically active elements found in Group 17 of the periodic table; the name applies especially to fluorine (symbol F), chlorine (Cl), bromine (Br), and iodine (I). ..... Click the link for more information. , and may have properties similar to astatineastatine [Gr.,=unstable], semimetallic radioactive chemical element; symbol At; at. no. 85; at. wt. of most stable isotope 210; m.p. 302°C; (estimated); b.p. 337°C; (estimated); density unknown; valence believed to be +1, +3, +5, or +7. ..... Click the link for more information. . In 2010 scientists from the Joint Institute for Nuclear Research in Dubna, Russia, announced that they had bombarded (2009) berkelium-249 atoms with calcium-48 ions to create two forms of tennessine. The Ts-294 isotope, with a half-life of 78 milliseconds, decayed through alpha-particle emission into dubnium (element 105), while the lighter Ts-293, with a half-life of 14 milliseconds, decayed down to roentgenium (element 111). The Russian researchers collaborated with American scientists at Vanderbilt Univ. and the Oak Ridge National Laboratory, which produced the berkelium used in the experiment. In 2015 the International Union of Pure and Applied Chemistry (IUPAC) confirmed the discovery. In 2016 the element's discoverers proposed the name tennessine, to honor the home state of the American collaborators, and the name was approved by IUPAC later that year. See also synthetic elementssynthetic elements, |
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