Dubnium element isotopes

Distillation, azeotropes, 6-177 to 195 Divergence, definition, A-68 to 74 DSC, definition, 12-1 to 4 DTA, definition, 12-1 to 4 Dubnium (element 105), 4-1 to 42,11-56 to 253 Dysprosium see also Elements electrical resistivity, 12-39 to 40 electron configuration, 1-18 to 19 heat capacity, 4-135 history, occurrence, uses, 4-1 to 42 ionization energy, 10-203 to 205 isotopes and their properties, 11-56 to 253 magnetic susceptibility, 4-142 to 147 molten, density, 4-139 to 141... 

ORIGIN OF NAME Unnilquadium follows the transitional naming system of lUPAC but originally was named "hahnium" by the Berkeley group in honor of Otto Hahn, who discovered nuclear fission. The American Chemical Society endorsed the name "hahnium" for element 105, but as the Berkeley group continued its work and more isotopes of Q Unp were formed, the lUPAC changed the name "hahnium" to "dubnium" after the city Dubna, Russia, where the first isotopes of unnilpentium were formed. 

The half life of most transfermium isotopes is only a few seconds or less. The half life of dubnium-260, for example, is 1.6 seconds. That means that half of the atoms in a sample will break down in 1.6 seconds and change to some other element. The short half lives of the transfermium isotopes make them hard to study. They tend to break down almost as soon as they are formed. Scientists have very litde time to observe them. 

In 1967, the JINR reported creation of a few atoms of element 105 with mass 261 and a lifetime of 1.8 seconds and reported other isotopes three years later. In 1970, the Berkeley group synthesized element 105 with mass 260 and tj/2 of 1.52 seconds but could not reproduce the 1967 Russian data. While the Berkeley group promoted hahnium as the name for element 105, lUPAC adopted the name dubnium (Db) in 1977. The most stable isotope (discovered in 2004 in Dubna) is ty 16 hours. 

In October 1971, it was announced that two new isotopes of Element 105 wa-e synthesized with the heavy ion Unear accelerator by A. Ghiorso and co-workers at Berkeley. Element 105 was produced both by bombarding s Cf with N and by bombarding Bk with The isotope emits 8.93-MeV a particles and decays to Lr with a half-life of about 1.8 s. Element 105 was produced by bombarding with 0. It emits 8.45 MeV a particles and decays to with a half-life of about 40 s. Nine isotopes of Dubnium are now recognized. Soon afro- the discovery the names... 

Though the " Ca-produced transactinide elements can be relatively resistant to spontaneous fission decay, the local increase in a-decay Q value with an increase in atomic number results in an overall decrease in half-life [329]. The decays of the " Ca-produced superheavy nuclei lead to chains of sequential a decays to longer lived daughter nuclei lying closer to the line of stability, some of which have surprisingly long half-lives. As an example, the decay of 115, produced in the AmC Ca,3n) reaction, results in a chain of a-emitting superheavy nuclei that culminates in Db (Z = 105), a nuclide with a half-life of one day [285, 286, 330]. This nuclide contains 7 neutrons more than the heaviest dubnium isotope that can be produced by either cold fusion or more asymmetric hot-fusion reactions. 

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