dubnium [doob′nē əm]
ModL, after Dubna, Russia, where important work in nuclear physics took place + -IUM
a radioactive chemical element with a very short half-life: a transactinide produced by bombarding californium or berkelium with high-energy nuclear particles: symbol, Db; at. no., 105: see the periodic table of elements in the Reference Supplement

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dub·ni·um (do͞obʹnē-əm) n. Symbol Db
An artificially produced radioactive element with atomic number 105 whose most long-lived isotopes have mass numbers of 258, 261, 262, and 263 with half-lives of 4.2, 1.8. 34, and 30 seconds, respectively. Also called unnilpentium. See table at element.
  [AfterDubna, Russia, the location of the United Institute of Nuclear Research.]

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 an artificially produced radioactive transuranium element in Group Vb of the periodic table, atomic number 105. The discovery of dubnium (element 105), like that of rutherfordium (element 104), has been a matter of dispute between Soviet and American scientists. The Soviets may have synthesized a few atoms of element 105 in 1967 at the Joint Institute for Nuclear Research in Dubna, Russia, U.S.S.R., by bombarding americium-243 with neon-22 ions, producing isotopes of element 105 having mass numbers of 260 and 261 and half-lives of 0.1 second and 3 seconds, respectively. Because the Dubna group did not propose a name for the element at the time they announced their preliminary data—a practice that has been customary following the discovery of a new element—it was surmised by American scientists that the Soviets did not have strong experimental evidence to substantiate their claims. Soviet scientists contended, however, that they did not propose a name in 1967 because they preferred to accumulate more data about the chemical and physical properties of the element before doing so. After completing further experiments, they proposed the name nielsbohrium.

      In 1970 a group of investigators at the Lawrence Radiation Laboratory of the University of California at Berkeley announced that they had synthesized isotope 260 of element 105, whereupon they proposed the name hahnium for the element, in honour of Otto Hahn (Hahn, Otto), the discoverer of nuclear fission. The American team could not duplicate the Soviet experiment; but, when its members bombarded californium-249 with the nuclei of nitrogen-15 atoms, they produced “hahnium-260,” which had a half-life of about 1.6 seconds. As further evidence of their discovery, the scientists at Berkeley measured the amount of energy emitted by “hahnium-260” as it decayed, as well as the elements produced in the process; these characteristics were quite different from those of previously known elements in the periodic system. The International Union of Pure and Applied Chemistry ultimately determined that the element be named dubnium.

atomic number
mass of moststable isotope
electronic config.
[Rn]5f 146d37s2

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Universalium. 2010.

Look at other dictionaries:

  • Dubnium — Rutherfordium ← Dubnium → Seaborgium Ta …   Wikipédia en Français

  • dubnium — (Db) Elemento transuránido. Su número atómico es 104; su peso atómico (masa) es 260. Se produce mediante una reacción nuclear inducida. También llamado elemento 105. Diccionario Mosby Medicina, Enfermería y Ciencias de la Salud, Ediciones… …   Diccionario médico

  • dubnium — ● dubnium nom masculin (de Dubna ou Doubna, nom propre) Élément chimique artificiel (Db) de numéro atomique 105, de masse atomique 262,1144 …   Encyclopédie Universelle

  • dubnium — Symbol: Db Competing name for unnilquadium, the 104th element, proposed by the IUPAC …   Elements of periodic system

  • dubnium — [doob′nē əm] n. [ModL, after Dubna, Russia, where important work in nuclear physics took place + IUM] a radioactive chemical element with a very short half life: a transactinide produced by bombarding californium or berkelium with high energy… …   English World dictionary

  • Dubnium — rutherfordium ← dubnium → seaborgium Ta ↑ Db ↓ (Upp) …   Wikipedia

  • Dubnium — Eigenschaften …   Deutsch Wikipedia

  • Dubnium — dubnis statusas T sritis fizika atitikmenys: angl. dubnium vok. Dubnium, n rus. дубний, m pranc. dubnium, m …   Fizikos terminų žodynas

  • dubnium — dubnis statusas T sritis chemija apibrėžtis Cheminis elementas. simbolis( iai) Db atitikmenys: lot. dubnium angl. dubnium rus. дубний …   Chemijos terminų aiškinamasis žodynas

  • dubnium — noun Etymology: New Latin, from Dubna, city in Russia where a center for investigation of heavy elements is located Date: 1994 a short lived radioactive element produced artificially see element table …   New Collegiate Dictionary

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