|Name , symbol , atomic number||Dubnium, Db, 105|
|Element category||Transition metals|
|Group , period , block||5 , 7 , d|
|Atomic mass||262,1138 u|
|Electron configuration||[ Rn ] 5 f 14 6 d 3 7 s 2 (?)|
|1. Ionization energy||6th.8 (5) eV ≈ 656 kJ / mol|
|2. Ionization energy||14th.0 (1.6) eV ≈ 1 350 kJ / mol|
|3. Ionization energy||23.1 (1.6 eV) ≈ 2 230 kJ / mol|
|4. Ionization energy||33.0 (1.7) eV ≈ 3 180 kJ / mol|
|5. Ionization energy||43.0 (1.9 eV) ≈ 4 150 kJ / mol|
|For other isotopes see list of isotopes|
|Hazard and safety information|
As far as possible and customary, SI units are used.
Unless otherwise noted, the data given apply to standard conditions .
Dubnium (formerly also: Hahnium , Nielsbohrium ) is an exclusively artificially produced chemical element with the element symbol Db and the atomic number 105. It is one of the transactinoids . In the periodic table of the elements it is in the 5th IUPAC group , the vanadium group . All Dubnium isotopes are radioactive .
Dubnium was discovered in 1967 by Georgi N. Flerow et al. at the United Institute for Nuclear Research at Dubna near Moscow and in 1970 by Albert Ghiorso et al. at the University of California , Berkeley . Like all transactinoids , Dubnium is artificially produced exclusively by particle bombardment. The Soviet working group worked with the bombardment of americium by neon cores and suggested the name Nielsbohrium for it:
So far, the element has only been synthesized in very small quantities for research purposes (in the experiments of Albert Ghiorso et al., For example, about 6 atoms per hour were produced) and has so far not been of any significance.
- Entry on dubnium in Kramida, A., Ralchenko, Yu., Reader, J. and NIST ASD Team (2019): NIST Atomic Spectra Database (ver. 5.7.1) . Ed .: NIST , Gaithersburg, MD. doi : 10.18434 / T4W30F ( https://physics.nist.gov/asd ). Retrieved June 13, 2020.
- Entry on dubnium at WebElements, https://www.webelements.com , accessed on June 13, 2020.
- The hazards emanating from radioactivity do not belong to the properties to be classified according to the GHS labeling. With regard to other hazards, this element has either not yet been classified or a reliable and citable source has not yet been found.
- Albert Ghiorso, Matti Nurmia, Kari Eskola, James Harris, Pirkko Eskola: New Element Hahnium, atomic number 105. In: Physical Review Letters , 1970 , 24 (26), pp 1498-1503; doi : 10.1103 / PhysRevLett.24.1498 .
- Entry on Dubnium. In: Römpp Online . Georg Thieme Verlag, accessed on August 3, 2020.