Bohrium was discovered in 1976 in Russia. It is radioactive and an artificially prepared element. Due to its instability it has no health effect and no significant industrial or biological role
History and Discovery
Bohrium is a synthetic element so its existence was discovered by two groups. First time in 1976 a team led by Yuri Oganessian (Russia), bombarded bismuth-209 and with chromium-54 and produced an isotope of a novel element that has an atomic mass of 261 and a half-life of around 2 millisecond. The existence of element was confirmed by German research team in 1981 by Peter Ambruster and Gottfried Munzenberg at the GSI (German Federal Research Institute) in Darmstadt bombarded bismuth-209 with nuclei of chromium-54 that led to the production of bohrium-262 isotope [1]. IUPAC (International Union of Pure and Applied Chemistry) in 1992 recognised the GSI as official discovers. Its named was originally proposed after Niels Bohr but later IUPAC changed the name of the 107th element to bohrium (Bh) [2].
Bohrium
| Periodic Table Classification | Group 7 Period 7 |
|---|---|
| State at 20C | Solid (predicted) |
| Color | Unknown |
| Electron Configuration | [Rn] 5f14 6d5 7s2 |
| Electron Number | 107 |
| Proton Number | 107 |
| Electron Shell | 2, 8, 18, 32, 32, 13, 2 |
| Density | 37.10 g.cm-3 at 20°C (predicted) |
| Atomic number | 107 |
| Atomic Mass | 264.00 g.mol -1 |
| Electronegativity according to Pauling | N/A |
Occurrence
Bohrium does not exists in nature. It is artificially produced and small amounts have been made. It is prepared artificially by bombarding bismuth-204 with chromium-54. The resulting reaction produced five atoms of bohrium.
Physical Characteristics
Bohrium is synthetic transition metal. It has been discovered in very minute amount. It is solid under normal conditions. It is malleable and able to conduct heat and electricity. Bohrium is heavy metal with the density of 37.1 g/cm3 and it is third highest of 118 known elements of the periodic table. It is heaviest member of group 7, its atomic number is 107 therefore it has same number of proton in the nucleus of each of its atom, and its atomic weight is 270 g/mol. Its melting point and boiling point still unknown.
Chemical Characteristics
Bohrium is radioactive element, its chemical properties are similar with the elements of group 7 and act as heavier homologue (series of compounds, different from each other by repeating units) with rhenium. Bohrium (VII) is unstable in aqueous solution and easily reduced to more stable bohrium (IV). It is also form volatile oxides Bh2O7. These oxides dissolve in water and form prebohric acid HBhO4. Bohrium exist in +7 oxidation state but it exhibit lower states like+3 and +4 that technetium and rhenium display.
Significance and Uses
- Bohrium has no know major application.
- It is only used for research purpose.
Health effects
Bohrium is very unstable compound, when it is formed it would decomposed to other elements very quickly that’s it has no different effect on human health.
Isotopes of Bohrium
Naturally bohrium has no stable isotopes but its isotopes have been synthesized in the laboratory. There are twelve artificially produced isotopes with atomic masses: 260-262, 264-267,270-274 and 278. Lighter isotopes like 260Bh, 261Bh, 262Bh have half- lives under 100ms. 264Bh, 265Bh, 266Bh and 271Bh have half-life around 1s, and 267Bh and 272Bh have half-lives about 10s. 270Bh and 274Bh have 61s and 40s, 278Bh have longer half-life of about 690s [3].
REFERENCES
[1]. http://www.rsc.org/periodic-table/element/107/bohrium
[2]. https://en.wikipedia.org/wiki/Bohrium
[3]. Sonzogni, Alejandro. “Interactive Chart of Nuclides”. National Nuclear Data Center: Brookhaven National Laboratory. Retrieved 2008-06-06.