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Dawn Angela Shaughnessy is an American radiochemist and principal investigator of the heavy element group at the Lawrence Livermore National Laboratory. [3] She was involved in the discovery of five superheavy elements with atomic numbers 114 to 118.
Superheavy elements, also known as transactinide elements, transactinides, or super-heavy elements, or superheavies for short, are the chemical elements with atomic number greater than 104. [1] The superheavy elements are those beyond the actinides in the periodic table; the last actinide is lawrencium (atomic number 103).
Despite these unsuccessful attempts to observe long-lived superheavy nuclei, [34] new superheavy elements were synthesized every few years in laboratories through light-ion bombardment and cold fusion [k] reactions; rutherfordium, the first transactinide, was discovered in 1969, and copernicium, eight protons closer to the island of stability ...
This name had been used in books of the Soviet Bloc as the official name of the element. The Americans, however, proposed rutherfordium (Rf) for the new element to honor New Zealand physicist Ernest Rutherford , who is known as the "father" of nuclear physics . [ 58 ]
The names einsteinium and fermium were suggested when their namesakes, respectively Albert Einstein and Enrico Fermi, were still alive; however, by the time the names became official, Einstein and Fermi had both died.) As Seaborg died in 1999, Oganessian is the only currently living namesake of an element. [41] [42] [43]
In 1996, the Russian team proposed the name becquerelium after Henri Becquerel. [59] The American team in 1997 proposed the name hahnium [60] after Otto Hahn (previously this name had been used for element 105). The name darmstadtium (Ds) was suggested by the GSI team in honor of the city of Darmstadt, where the element was discovered.
As some superheavy elements were predicted to lie beyond the seven-period periodic table, an additional eighth period containing these elements was first proposed by Glenn T. Seaborg in 1969. This model continued the pattern in established elements and introduced a new g-block and superactinide series beginning at element 121, raising the ...
The JINR–LLNL claim to elements 115 and 113 had been founded on chemical identification of their daughter dubnium, but the JWP objected that current theory could not distinguish between superheavy group 4 and group 5 elements by their chemical properties with enough confidence to allow this assignment. [64]