| Atomic Mass | 268 |
|---|---|
| Electron Configuration | [Rn]7s25f146d3 |
| Oxidation States | 5, (4), (3) (parenthesized oxidation states are predictions) |
| Year Discovered | 1967 |
| Atomic Mass | 268 |
|---|---|
| Electron Configuration | [Rn]7s25f146d3 |
| Oxidation States | 5, (4), (3) (parenthesized |
| Year Discovered | 1967 |
| Element Name | Dubnium |
|---|---|
| Element Symbol | Db |
| InChI | InChI=1S/Db |
| InChIKey | PUKKTGLVJQVIOF-UHFFFAOYSA-N |
| Atomic Weight |
268 268 Relative Mass: 268.12567(57#) |
|---|---|
| Electron Configuration |
[Rn]7s25f146d3 |
| Atomic Radius |
Empirical Atomic Radius : empirical: 139 pm (estimated) |
| Oxidation States |
5, (4), (3) (parenthesized oxidation states are predictions) |
| Ground Level |
4F3/2 |
| Ionization Energy |
6.8 ± 0.5 eV (Theoretical value.) |
| Atomic Spectra |
Levels Holdings |
| Physical Description |
Solid |
| Element Classification |
Metal |
| Element Period Number |
7 |
| Element Group Number |
5 |
| Estimated Crustal Abundance |
Not Applicable |
| Estimated Oceanic Abundance |
Not Applicable |
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-268, has a half-life of about 32 hours and decays through spontaneous fission.
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. The evidence was based on time-coincidence measurements of alpha energies.
In 1970 Dubna scientists synthesized Element 105 and, by the end of April 1970, "had investigated all the types of decay of the new element and had determined its chemical properties," according to a report in 1970. The Soviet group had not proposed a name for 105. In late April 1970, it was announced that Ghiorso, Nurmia, Haris, 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 a15N nuclear 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. The Berkeley Group proposed the name hahnium after the late German scientist Otto Hahn (1879-1968) and symbol Ha. However, the International Union of Pure and Applied Chemistry panel members in 1977 recommended that element 105 be named to Dubnium (symbol Db) after the site of the Joint Institute for Nuclear Research in Russia. Unfortunately, the name hahnium will not be used again according to the rules for naming new elements. Some scientists still use the earlier name of hahnium because it had been used for about 25 years.
Dubnium does not occur naturally in the Earth’s crust. Credit for the first synthesis of this element is given jointly to Albert Ghiorso and his team at the University of California in Berkeley and Georgi Flerov and his team at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia (Fig. IUPAC.105.1). The element is named for the location of the Joint Institute for Nuclear Research (JINR) laboratory in Dubna, Russia [646], [647]. Dubnium has no isotopic applications outside of scientific research.
![Fig. IUPAC.105.1: Photo of the cyclotron U-300 used to synthesize dubnium. This is a 300-cm heavy-ion cyclotron built at the International Joint Institute for Nuclear Research (JINR) and put into operation in 1960. (Photo used with permission from Ivo J. Zvara, Joint Institute for Nuclear Research (JINR)). (Photo Source: Ivo J. Zvara, American Chemical Society, 2003) [646].](https://pubchem.ncbi.nlm.nih.gov/images/iupac/j_pac-2015-0703_fig_141.jpg)
Dubnium is named after the site of the Joint Institute for Nuclear Research in Dubna, Russia.
Due to the small amounts produced and its short half-life, there are currently no uses for dubnium outside of basic scientific research.
See more information at the Dubnium compound page.
| CID | Name | Formula | SMILES | Molecular Weight |
|---|---|---|---|---|
| 56951718 | dubnium | Db | [Db] | 268.126 |
| Stable Isotope Count | 0 |
|---|---|
| Summary | 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 a Berkeley. Element 261105 was produced both by bombarding 250Cf with 15N and by bombarding 249Bk with 16O. The isotope emits 8.93-MeV alpha 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 alpha particles and decays to 258Lr with a half-life of about 40 s. Seven isotopes of element 105 (unnilpentium) are now recognized. |
| Isotope | Atomic Mass (uncertainty) [u] | Abundance (uncertainty) |
|---|---|---|
| 268Db | 268.12567(57#) |
| Nuclide | Atomic Mass and Uncertainty [u] | Half Life and Uncertainty | Discovery Year | Decay Modes, Intensities and Uncertainties [%] |
|---|---|---|---|---|
| 255Db | 255.106919 ± 0.000304 [Estimated] | 54 ms | 1976 | SF≈67%; α ? |
| 255Dbm | 255.106919 ± 0.000304 [Estimated] | 2.8 ms | 1976 | SF≈100%; α ? |
| 256Db | 256.107674 ± 0.000201 [Estimated] | 1.7 s ± 0.4 | 2001 | α=70±1.1%; β+=30±1.1%; SF ? |
| 257Db | 257.107520042 ± 0.000176741 | 2.3 s ± 0.2 | 1985 | α>94%; SF<6%; β+ ? |
| 257Dbm | 257.107520042 ± 0.000176741 | 670 ms ± 60 | 1985 | α>87%; SF<13%; β+ ? |
| 258Db | 258.108972995 ± 0.000098613 | 2.17 s ± 0.36 | 1985 | α=64±1%; β+=36±1% |
| 258Dbm | 258.108972995 ± 0.000098613 | 4.41 s ± 0.21 | 1981 | α=77±0.8%; β+=23±0.8%; SF ? |
| 259Db | 259.109491859 ± 0.000060854 | 510 ms ± 160 | 2001 | α=100% |
| 260Db | 260.111297 ± 0.0001 [Estimated] | 1.52 s ± 0.13 | 1970 | α=90.4±0.6%; SF=9.6±0.6%; β+ ? |
| 261Db | 261.111979 ± 0.000118 [Estimated] | 4.7 s ± 1.0 | 1970 | SF=73±1.1%; α=27±1.1% |
| 262Db | 262.114067 ± 0.000154 [Estimated] | 34 s ± 4 | 1971 | SF=52±0.4%; α=48±0.4%; β+ ? |
| 262Dbp | 262.114067 ± 0.000154 [Estimated] | Not-specified | α ? | |
| 263Db | 263.114987 ± 0.00018 [Estimated] | 29 s ± 9 | 1992 | SF=56±1.4%; α=37±1.4%; β+=6.9±1.6% |
| 264Db | 264.117297 ± 0.000253 [Estimated] | 3 m [Estimated] | α ? | |
| 265Db | 265.118500 ± 0.00024 [Estimated] | 15 m [Estimated] | α ? | |
| 266Db | 266.121032 ± 0.000304 [Estimated] | 80 m ± 70 | 2007 | α ?; SF=?; β+ ? |
| 267Db | 267.122399 ± 0.000402 [Estimated] | 2.0 h ± 1.1 | 2004 | SF=100% |
| 268Db | 268.125669 ± 0.000568 [Estimated] | 29 h ± 3 | 2004 | SF≈100%; β+ ?; α ? |
| 269Db | 269.127911 ± 0.000669 [Estimated] | 3 h [Estimated] | α ?; SF ? | |
| 270Db | 270.131399 ± 0.000617 [Estimated] | 1.7 h ± 1.0 | 2010 | SF≈87%; α≈13% |
