Bohrium

group 7 · period 7 · d-block · transition metal

Identity

Name and symbol: Bohrium, Bh
Atomic number: 107 protons
Position: group 7 · period 7 · d-block · transition metal
CAS number: 54037-14-8

Atomic structure

Atomic mass: 270 u
Electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d⁵
[Rn] 7s²⁵f¹⁴⁶d⁵
Electrons per shell: 2, 8, 18, 32, 32, 13, 2
Valence electrons: 7 ns and (n-1)d

nuclide	half-life	decay
²⁷⁰Bh	3.8 m	α=100%
²⁶⁸Bh	190 s [Estimated]	α ?; SF ?
²⁶⁹Bh	1 m [Estimated]	α ?
²⁷³Bh	1 m [Estimated]	α ?; SF ?

no stable isotope; the longest-lived nuclides

Physical properties

State at room temperature: Solid
Melting point: not in sources
Boiling point: not in sources
Density: not in sources
Appearance: not in sources
Thermal conductivity: not in sources
Electrical resistivity: not in sources
Electrical conductivity: not in sources
Crystal structure: hexagonal close-packed
Molar heat capacity: not in sources

Chemical properties

Oxidation states: 7, (5), (4), (3) (parenthesized oxidation states are predictions)
Electronegativity: not in sources
Ionisation energy: 7.7 eV
Electron affinity: not in sources
Atomic radius: not in sources
Ionic radius: not in sources

Reactivity: A group 7 transactinide; a 2000 experiment on six atoms showed it forms a volatile oxychloride like technetium and rhenium, confirming typical group 7 behavior in the +7 state.
with water: Not known; no experiment has been reported.
with oxygen, air: Only in combination with hydrogen chloride: single atoms in an oxygen and HCl stream form the oxychloride: $\ce{2 Bh + 3 O2 + 2 HCl -> 2 BhO3Cl + H2}$ .
with acids: Not known; no aqueous experiment has been reported.
with halogens: With chlorine only as the oxychloride BhO3Cl, less volatile than TcO3Cl and ReO3Cl.

Typical compounds

BhO₃Cl bohrium oxychloride volatile, detected on six atoms in 2000

Occurrence, production and use

Crustal abundance: Not Applicable
Oceanic abundance: Not Applicable

Occurrence and sources

synthetic only bismuth bombarded with chromium atoms (cold fusion)

Extraction, production: not in sources

Uses: Since only a few atoms of bohrium have ever been made, there are currently no uses for bohrium outside of basic scientific research.

Safety, toxicity: not in sources

Discovery and name

Discovered by: Gesellschaft für Schwerionenforschung
Discovered: 1981
First isolated: not in sources
Named by: not in sources
Origin of the name: after Niels Bohr

Bohrium does not occur naturally in the Earth’s crust. Bohrium was first synthesized by German scientists at the GSI Center for Heavy Ion Research in Darmstadt, Germany in 1981 using the nuclear reaction 209Bi (54Cr, n) 262Bh. The element is named for Niels Bohr (Fig. IUPAC.107.1), the Nobel Prize winning physicist [649], [650]. Bohrium has no known isotopic applications aside from scientific research.

Bohrium is named after Niels Bohr.

Conventions

Valence electrons are counted by the usual convention: the outer shell for s- and p-block elements, ns and (n-1)d for the d-block, ns, (n-1)d and (n-2)f for the f-block. Lanthanides and actinides are placed in the f-block with no group number. Electrical conductivity is the reciprocal of the printed resistivity. Ionic radii are Shannon effective radii, six-coordinate unless noted. Where a field reads “not in sources” the value was not found; it is a gap, not a zero. Regulatory limits are the published values and change often, so check the standard in force at your site and the numbers written into your own permit before you design to them.

Data

Element records, isotopes, radii and the descriptive text come from PubChem (NCBI), the Los Alamos National Laboratory periodic table, IUPAC CIAAW and the IAEA Atomic Mass Data Center. Appearance, thermal conductivity, electrical resistivity, crystal structure, discovery and the origin of each name come from Wikipedia and Periodic-Table-JSON, used under CC BY-SA 4.0. Hazard classifications come from the ECHA C&L inventory via PubChem. Ionic radii follow R. D. Shannon (1976). The water chapters cite their own sources at the foot of each entry, and are written to the level of Snoeyink and Jenkins, Stumm and Morgan, MWH's Water Treatment and Metcalf and Eddy.