   #copyright

Nobelium

2007 Schools Wikipedia Selection. Related subjects: Chemical elements


              102            mendelevium ← nobelium → lawrencium
              Yb
             ↑
             No
             ↓
             (Upb)

                                  Periodic Table - Extended Periodic Table

                                                                   General
                                    Name, Symbol, Number nobelium, No, 102
                                                 Chemical series actinides
                                            Group, Period, Block n/a, 7, f
                                      Appearance unknown, probably silvery
                                                    white or metallic gray
                                                   Atomic mass (259) g/mol
                                    Electron configuration [Rn] 5f^14 7s^2
                                Electrons per shell 2, 8, 18, 32, 32, 8, 2
                                                       Physical properties
                                                               Phase solid
                                                     Melting point 1100  K
                                                     (827 ° C, 1521 ° F)
                                                         Atomic properties
                                     Electronegativity 1.3 (Pauling scale)
                                       Ionization energies 1st: 642 kJ/mol
                                                             Miscellaneous
                                            CAS registry number 10028-14-5
                                                         Selected isotopes

   CAPTION: Main article: Isotopes of nobelium

                                   iso   NA  half-life DM DE ( MeV)   DP
                                  ^253No syn 1.7 m     α  8.440     ^249Fm
                                                       ε  3.200     ^253Md
                                  ^255No syn 3.1 m     α  8.445     ^251Fm
                                                       ε  2.012     ^255Md
                                  ^259No syn 58 m      α  7.910     ^255Fm
                                                       ε  0.500     ^259Md
                                                       SF -         -

                                                                References

   Nobelium ( IPA: /ˌnə(ʊ)ˈbiːliəm/), also known as unnilbium ( IPA:
   /ˌjuːˈnɪlbiəm/, symbol Unb), is a synthetic element in the periodic
   table that has the symbol No and atomic number 102. A radioactive
   metallic transuranic element in the actinide series, nobelium is
   synthesized by bombarding curium with carbon ions. It was first
   identified by a team led by Albert Ghiorso and Glenn T. Seaborg in
   1958.

Notable characteristics

   Little is known about nobelium and only small quantities of it have
   ever been produced. It has no uses whatsoever outside of the
   laboratory. Its most stable isotope, ^259No, has a half-life of 58
   minutes and decays to ^255Fm through alpha decay or to ^259Md through
   electron capture.

History

   Nobelium (named for Alfred Nobel) was first synthesized by Albert
   Ghiorso, Glenn T. Seaborg, John R. Walton and Torbjørn Sikkeland in
   April 1958 at the University of California, Berkeley. The team used the
   new heavy- ion linear accelerator (HILAC) to bombard a curium target
   (95% ^244Cm and 4.5% ^246Cm) with ^12C ions to make ^254No ( half-life
   55 seconds). Their work was confirmed by Soviet researchers in Dubna.

   A year earlier, however, physicists at the Nobel Institute in Sweden
   announced that they had synthesized an isotope of element 102. The team
   reported that they created an isotope with a half-life of 10 minutes at
   8.5 MeV after bombarding ^244Cm with ^13C nuclei. Based on this report,
   the Commission on Atomic Weights of the International Union of Pure and
   Applied Chemistry assigned and accepted the name nobelium and the
   symbol No for the "new" element. Subsequent Russian and American
   efforts to repeat the experiment failed.

   In 1966 researchers at UC Berkeley confirmed the 1958 experiments and
   went on to show the existence of ^254No (half-life 55 s), ^252No
   (half-life 2.3 s), and ^257No (half-life 23 s). The next year Ghiorso's
   group decided to retain the name nobelium for element 102.

   Nobelium was the most recent element "of which the news had come to
   Harvard" when Tom Lehrer wrote " The Elements Song" and was therefore
   the element with the highest atomic number to be included.

Isotopes

   13 radioisotopes of nobelium have been characterized, with the most
   stable being ^259No with a half-life of 58 minutes, ^255No with a
   half-life of 3.1 minutes, and ^253No with a half-life of 1.7 minutes.
   All of the remaining radioactive isotopes have half-lifes that are less
   than 56 seconds, and all of these have half lifes that are less than
   2.4 seconds. This element also has 1 meta state, ^254mNo (t[½] 0.28
   seconds).

   The known isotopes of nobelium range in atomic weight from 249.088 u
   (^249No) to 262.108 u (^262No). The primary decay mode before the most
   stable isotope, ^259No, is alpha emission, and the primary mode after
   is spontaneous fission. The primary decay products before ^259No are
   element 100 (fermium) isotopes, and the primary products after are
   energy and subatomic particles.
   Retrieved from " http://en.wikipedia.org/wiki/Nobelium"
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   with only minor checks and changes (see www.wikipedia.org for details
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