   #copyright

Dubnium

2007 Schools Wikipedia Selection. Related subjects: Chemical elements


              105           rutherfordium ← dubnium → seaborgium
              Ta
             ↑
             Db
             ↓
             (Upp)

                                  Periodic Table - Extended Periodic Table

                                                                   General
                                     Name, Symbol, Number dubnium, Db, 105
                                         Chemical series transition metals
                                              Group, Period, Block 5, 7, d
                                      Appearance unknown, probably silvery
                                                    white or metallic gray
                                                   Atomic mass (268) g/mol
                       Electron configuration perhaps [Rn] 5f^14 6d^3 7s^2
                                                 (guess based on tantalum)
                               Electrons per shell 2, 8, 18, 32, 32, 11, 2
                                                  Phase presumably a solid
                                            CAS registry number 53850-35-4
                                                                References

   Dubnium ( IPA: /ˈduːbniəm/), also called eka-tantalum, is a chemical
   element in the periodic table that has the symbol Db and atomic number
   105. This is a highly radioactive synthetic element whose most stable
   isotope has a half life of 32 hours (^268Db). This relatively high
   stability compared to the surrounding elements on the periodic table
   gives evidence that by manipulating the number of neutrons in a
   nucleus, one can alter the stabilities of such nuclei.

History

   Dubnium (named after Dubna, Russia) was reportedly first synthesized in
   1967 at the Joint Institute for Nuclear Research in Dubna, Russia
   (reportedly producing nuclide ^260105 and nuclide ^261105 by bombarding
   ^243Am with ^22Ne). In late April 1970 researchers led by Albert
   Ghiorso working at the University of California, Berkeley had
   positively identified element 105.

   The American team synthesized the element by bombarding a target ^249Cf
   with a beam of 84 MeV nitrogen nuclei in the Heavy Ion Linear
   Accelerator (a particle accelerator), which produced nuclide ^260105
   with a half-life of 1.6 seconds. Atoms of element 105 were detected
   conclusively on March 5, 1970 but there is evidence that this element
   had already been formed at Berkeley a year earlier using the same
   method.

   The Berkeley scientists later tried to confirm the Soviet findings
   using more sophisticated methods but were not successful. They proposed
   that the new element should be named hahnium (symbol Ha) in honour of
   the late German scientist Otto Hahn. Consequently this was the name
   that most American and Western European scientists used.

   An element naming controversy erupted over what to name this element
   after Russian researchers protested. The International Union of Pure
   and Applied Chemistry (IUPAC) thus adopted unnilpentium ( IPA:
   /ˌjuːnɪlˈpɛntiəm/, symbol Unp) as a temporary, systematic element name.
   However in 1997 they resolved the dispute and adopted the current name,
   dubnium (symbol Db), after the city that contains the Russian Joint
   Institute for Nuclear Research. Its former names have included hahnium
   ( IPA: /ˈhɑːniəm/), joliotium ( IPA: /ˌdʒəʊliˈəʊtiəm/) and nielsbohrium
   ( IPA: /ˌnɪəlsˈbɔː(h)riəm/).
   Retrieved from " http://en.wikipedia.org/wiki/Dubnium"
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   with only minor checks and changes (see www.wikipedia.org for details
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