Bohrium is an artificially produced radioactive chemical element with the symbol Bh and the atomic number 107 in the periodic table of elements. It’s not found in Earth’s crust since it’s a synthetic element created in a laboratory.
Chemical and Physical Properties of Bohrium
The symbol in the periodic table of elements: (Bh)
Atomic number: 107
Atomic weight (mass): 264.00 g.mol -1
Group number: 7
Physical state: Solid (predicted) on a room temperature
Half-life: 17 seconds
Electronegativity according to Pauling: Unknown
Density: 37.10 g.cm-3 at 20°C (predicted)
Melting point: Unknown
Boiling point: Unknown
Van der Waals radius: Unknown
Ionic radius: Unknown
Isotopes: No stable isotopes
Most characteristic isotope: bohrium-270
The energy of the first ionization: 740 kJ/mol
The energy of the second ionization: 1690 kJ/mol
The energy of the second ionization: 2570 kJ/mol
Discovery date: In 1976 by Peter Armbruster and Gottfried Munzenberg
With an atomic number larger than uranium, electron configuration [Rn] 5f14 6d5 7s2, predicted density of 37.10 g.cm-3 at 20°C, and an atomic mass of 264.00 g.mol -1, bohrium belongs to the group of heavy metal elements, placed third by weight among other chemical elements.
Even though this element is still not sufficiently researched, the experiments conducted on the oxychloride of bohrium provide evidence that this transition metal shares known chemical properties with the elements of group 7 in the periodic table, particularly with the rare metal rhenium.
How Was Bohrium Discovered?
In 1976, the Russian nuclear physicist of Armenian descent, Yuri Oganessian, conducted an experiment with a team of Soviet researchers. At the Joint Institute for Nuclear Research in Dubna, Russia, they bombarded lead-208 and bismuth-209 with manganese-55 and chromium-54 isotopes.
The observation of the result led them to the discovery of bohrium. Unfortunately, the IUPAC/IUPAP Transfermium Working Group (TWG) believed that more convincing evidence was needed in order to officialize the discovery of a new element.
Five years later, in 1981, the German physicists, Peter Armbruster and Gottfried Münzenberg, from the Gesellschaft für Schwerionenforschung at the Heavy Ion Research Laboratory (GSI Helmholtzzentrum für Schwerionenforschung) in Darmstadt, Germany, managed to produce five bohrium-262 isotopes with a cold fusion reaction by bombarding bismuth-209 with chromium-54 isotopes.
Additionally, these two scientists also managed to provide scientific evidence for the alpha decay chain of the produced bohrium isotopes to fermium (Fm) and californium (Cf). This earned them a place in the history of science as the discoverers of a new chemical element of the periodic table labeled as bohrium.
How Did Bohrium Get Its Name?
This member of the transactinides family in the periodic table elements got its name in honor of Danish physicist Niels Bohr (7 October, 1885 – 18 November, 1962). The proposed name by the scientists who had discovered the new element was nielsbohrium with the symbol (Ns).
Until the name of the new element was agreed upon, this element was temporarily labeled as unnilseptium (Uns) by the IUPAC. In 1991 the first proposal was adopted in a shortened form and announced by the International Union of Pure and Applied Chemistry.
Where Can You Find Bohrium?
Since bohrium is a man-made, synthetic element, it cannot be found in its elemental form in nature.
Bohrium in the Everyday Life
So far, bohrium has been used only for scientific purposes.
How Dangerous Is Bohrium?
Despite being a radioactive substance and potentially hazardous, the half life of this transition metal is only 17 seconds, which makes this chemical element unstable, having no harmful effects upon the environment or human health.
Isotopes of Bohrium
All bohrium isotopes are extremely radioactive. With a half-life of 61 seconds, bohrium-270 is the most stable isotope that decays into dubnium-266 through an alpha decay.
|Z||N||Isotopic mass (Da)
[n 2][n 3]
|261Bh||107||154||261.12146(22)#||12.8(3.2) ms||α (95%?)||257Db||(5/2−)|
|262Bh||107||155||262.12297(33)#||84(11) ms||α (80%)||258Db|
|262mBh||220(50) keV||9.5(1.6) ms||α (70%)||258Db|
|264Bh[n 6]||107||157||264.12459(19)#||1.07(21) s||α (86%)||260Db|
|266Bh[n 7]||107||159||266.12679(18)#||2.5(1.6) s||α||262Db|
|270Bh[n 8]||107||163||270.13336(31)#||61 s||α||266Db|
|271Bh[n 9]||107||164||271.13526(48)#||1.5 s||α||267Db|
|272Bh[n 10]||107||165||272.13826(58)#||8.8(2.1) s||α||268Db|
|274Bh[n 11]||107||167||274.14355(65)#||0.9 min||α||270Db|
|278Bh[n 12]||107||171||11.5 min?||SF||(various)|
5 Interesting Facts and Explanations
- From all elements in the periodic table, only meitnerium (37.4 g/cm3) and hassium (41 g/cm3) are heavier than bohrium.
- The group of transuranium elements is made up of americium, curium, californium, neptunium, plutonium, mendelevium, nobelium, berkelium, einsteinium, fermium, and lawrencium.
- The common oxidation state for all of the group 7 elements is +7.
- The predicted atomic radius of bohrium is 128 pm.
- The crystal structure of bohrium has a hexagonal close-packed formation.