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Lawrencium

2007 Schools Wikipedia Selection. Related subjects: Chemical elements


              103           nobelium ← lawrencium → rutherfordium
              Lu
             ↑
             Lr
             ↓
             (Upt)

                                  Periodic Table - Extended Periodic Table

                                                                   General
                                  Name, Symbol, Number lawrencium, Lr, 103
                                         Chemical series Transition metals
                                              Group, Period, Block 3, 7, d
                                      Appearance unknown, probably silvery
                                                    white or metallic gray
                                                   Atomic mass (262) g/mol
                      Electron configuration probably [Rn] 5f^14 7s^2 7p^1
                                Electrons per shell 2, 8, 18, 32, 32, 8, 3
                                                  Phase presumably a solid
                                                     Melting point 1900  K
                                                    (1627 ° C, 2961 ° F)
                                       Ionization energies 1st: 470 kJ/mol
                                            CAS registry number 22537-19-5
                                                                References

   Lawrencium ( IPA: /ləˈrɛnsiəm/), also called eka-lutetium, is a
   radioactive synthetic element in the periodic table that has the symbol
   Lr and atomic number 103. Its most stable isotope is ^262Lr, with a
   half-life of approximately 4 hours. Lawrencium is synthesized from
   californium and has no known uses.

Notable characteristics

   The appearance of this element is unknown, however it is most likely
   silvery-white or gray and metallic. If sufficient amounts of lawrencium
   were produced, it would pose a radiation hazard. Very little is known
   about the chemical properties of this element but some preliminary work
   on a few atoms has indicated that it behaves similarly to the
   actinides.

   Element 103 is a d-block element analogous to lutetium and therefore is
   increasingly being placed with the other d-block elements in the
   transition metal chemical series, but it is still sometimes grouped
   with the actinides in the periodic table.

History

   Lawrencium was discovered by Albert Ghiorso, Torbjørn Sikkeland, Almon
   Larsh and Robert M. Latimer on February 14, 1961 at the Berkeley
   Radiation Laboratory (now called Lawrence Berkeley National Laboratory)
   on the University of California, Berkeley campus. It was produced by
   bombarding a 3 milligram target composed of three isotopes of
   californium with boron-10 and B-11 ions in the Heavy Ion Linear
   Accelerator (HILAC).

   The transmutation nuclei became electrically charged, recoiled with a
   helium atmosphere and were collected on a thin copper conveyor tape.
   This tape was then moved in order to place the collected atoms in front
   of a series of solid-state detectors. The Berkeley team reported that
   the isotope ^257103 was detected in this manner and decayed by emitting
   an 8.6 MeV alpha particle with a half-life of 4.2 seconds.

   In 1967, researchers in Dubna, Russia reported that they were not able
   to confirm an alpha emitter with a half-life of 4.2 seconds as ^257103.
   This assignment has since been changed to ^258Lr or ^259Lr. Eleven
   isotopes of element 103 have been synthesized with ^262Lr being the
   longest lived with a half-life of 216 minutes (it decays into ^256No.
   The isotopes of lawrencium decay via alpha emission, spontaneous
   fission and electron capture (in order of most to least common types).

   The origin of the name, preferred by the American Chemical Society, is
   in reference to Ernest O. Lawrence, inventor of the cyclotron. The
   symbol Lw was originally used but in 1963 it was changed to Lr. In
   August 1997 the International Union of Pure and Applied Chemistry
   (IUPAC) ratified the name lawrencium and symbol Lr during a meeting in
   Geneva. Unniltrium ( IPA: /ˌjuːˈnɪltriəm/, symbol Unt) was sometimes
   used as a temporary, systematic element name until that time.
   Retrieved from " http://en.wikipedia.org/wiki/Lawrencium"
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   with only minor checks and changes (see www.wikipedia.org for details
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