Dubnium

Radioactive and Artificially Produced Scientists working at the Joint Institute for Nuclear Research in Dubna, Russia, first reported the production of dubnium in 1967. They bombarded atoms of americium-243 with ions of neon-22, forming atoms of dubnium-260 and five free neutrons and atoms of dubnium-261 and four free neutrons. In 1970, a group of scientists working at the Lawrence Radiation Laboratory, now known as the Lawrence Berkeley Laboratory, in Berkeley, California, bombarded atoms of californium-249 with ions of nitrogen-15, forming atoms of dubnium-260 and 4 free neutrons. Credit for the discovery of dubnium is still under debate. Dubnium's most stable isotope, dubnium-270, has a half-life of about 33.4 hours and decays through spontaneous fission. Due to the small amounts produced and its short half-life, there are currently no uses for dubnium outside of basic scientific research. In the [|periodic table] of the elements, it is a [|d-block] element and in the [|transactinide elements]. It is a member of the [|7th period] and belongs to the [|group 5 element]. Chemistry experiments have confirmed that dubnium behaves as the heavier [|homologue] to [|tantalum] in group 5. The chemical properties of dubnium are characterized only partly. They are similar with those of other group 5 elements. In the 1960s, microscopic amounts of dubnium were produced in laboratories in the former [|Soviet Union] and in [|California]. The priority of the discovery and therefore the [|naming of the element] was disputed between Soviet and American scientists, and it was not until 1997 that [|International Union of Pure and Applied Chemistry] (IUPAC) established Soviet team priority and a compromise name of dubnium as the official name for the element.
 * Atomic Number:** 105
 * Atomic Weight:** 270
 * Melting Point:** Unknown
 * Boiling Point:** Unknown
 * Density:** Unknown
 * Phase at Room Temperature:** Solid
 * Element Classification:** Metal
 * Period Number:** 7 **Group Number:** 5 **Group Name:** none
 * What's in a name?** Named for the Joint Institute for Nuclear Research at Dubna, Russia.
 * Say what?** Dubnium is pronounced as **DUB-nee-em**.
 * History and Uses:**
 * Estimated Crustal Abundance:** Not Applicable
 * Estimated Oceanic Abundance:** Not Applicable
 * Number of Stable Isotopes:** 0
 * Ionization Energy:** Unknown
 * Oxidation State:** Unknown
 * Dubnium** is a [|chemical element] with the symbol **Db** and [|atomic number] 105, named after the town of [|Dubna] in [|Russia], where it was first produced. It is a [|synthetic element] (an element that can be created in a laboratory but is not found in nature) and radioactive; the most stable known [|isotope], dubnium-268, has a [|half-life] of approximately 28 hours. [|[][|5][|]]

Isomerism 260Db Recent data on the decay of 272Rg has revealed that some decay chains continue through 260Db with extraordinary longer life-times than expected. These decays have been linked to an isomeric level decaying by alpha decay with a half-life of ~19 s. Further research is required to allow a definite assignment. 258Db Evidence for an isomeric state in 258Db has been gathered from the study of the decay of 266Mt and 262Bh. It has been noted that those decays assigned to an electron capture (EC) branch has a significantly different half-life to those decaying by alpha emission. This has been taken to suggest the existence of an isomeric state decaying by EC with a half-life of ~20 s. Further experiments are required to confirm this assignment. 257Db A study of the formation and decay of 257Db has proved the existence of an isomeric state. Initially, 257Db was taken to decay by alpha emission with energies 9.16,9.07 and 8.97 MeV. A measurement of the correlations of these decays with those of 253Lr have shown that the 9.16 MeV decay belongs to a separate isomer. Analysis of the data in conjunction with theory have assigned this activity to a meta stable state, 257mDb. The ground state decays by alpha emission with energies 9.07 and 8.97 MeV. Spontaneous fission of 257m,gDb was not confirmed in recent experiments.