Chemical Fact Sheet


Chemical Abstract Number (CAS #) 53850-35-4
Analytical Methods 200.8 - 6020
Atomic Symbol Db

Synopsis from the CRC Handbook of Chemistry and Physics 92nd Edition 2011-2013

Dubnium — (named after the Joint Institute of Nuclear Research in Dubna, Russia). Db; at. wt. [262]; at. no. 105. In 1967 G. N. Flerov reported that a Soviet team working at the Joint Institute for Nuclear Research at Dubna may have produced a few atoms of 260105 and 261105 by bombarding 243Am with 22Ne. Their evidence was based on time-coincidence measurements of alpha energies. More recently, it was reported that early in 1970 Dubna scientists synthesized Element 105 and that by the end of April 1970 “had investigated all the types of decay of the new element and had determined its chemical properties.” In late April 1970, it was announced that Ghiorso, Nurmia, Harris, K. A. Y. Eskola, and P. L. Eskola, working at the University of California at Berkeley, had positively identified Element 105. The discovery was made by bombarding a target of 249Cf with a beam of 84 MeV nitrogen nuclei in the Heavy Ion Linear Accelerator (HILAC). When a 15N nucleus is absorbed by a 249Cf nucleus, four neutrons are emitted and a new atom of 260105 with a half-life of 1.6 s is formed. While the first atoms of Element 105 are said to have been detected conclusively on March 5, 1970, there is evidence that Element 105 had been formed in Berkeley experiments a year earlier by the method described. Ghiorso and his associates have attempted to confirm Soviet findings by more sophisticated methods without success. In October 1971, it was announced that two new isotopes of Element 105 were synthesized with the heavy ion linear accelerator by A. Ghiorso and co-workers at Berkeley. Element 261105 was produced both by bombarding 250Cf with 15N and by bombarding 249Bk with 16O. The isotope emits 8.93- MeV α particles and decays to 257Lr with a half-life of about 1.8 s. Element 262105 was produced by bombarding 249Bk with 18O. It emits 8.45 MeV α particles and decays to 258Lr with a half-life of about 40 s. Nine isotopes of Dubnium are now recognized. Soon after the discovery the names Hahnium and Joliotium, named after Otto Hahn and Jean-Frederic Joliot and Mme. Joliot-Curie, were suggested as names for Element 105. The IUPAC in August 1997 finally resolved the issue, naming Element 105 Dubnium with the symbol Db. Dubnium is thought to have properties similar to tantalum.
Consumption Patterns
Apparent Color
Boiling Point
Melting Point
Molecular Weight

Chemical and

Physical Properties



Environmental Fate

Drinking Water




DISCLAIMER - Please Read

Return to :

Florida-Spectrum List of Services
Florida-Spectrum Homepage