Bohrium
Transition metal · Period 7 · Group 7 · d-block
Niels Bohr's element, studied as a single molecule at a time
- Atomic mass
- 270 u
- State at 25 °C
- Solid
- Electronegativity
- —
- Melting point
- —
- Boiling point
- —
- Configuration
- *[Rn] 5f14 6d5 7s2
Nucleus drawn at reduced count for clarity. Drag to rotate.
Bohrium, explained
Video lesson in production
Bhavya’s explainer for this element will play here.
Overview
Bohrium is a group 7 element under manganese, technetium and rhenium, with a predicted 7s2 6d5 configuration. Its expected highest oxidation state is +7, matching rhenium's in compounds such as ReO3Cl. That prediction was tested directly in 2000, when a team at the Paul Scherrer Institute in Switzerland formed bohrium oxychloride, BhO3Cl, and compared its volatility with the rhenium and technetium analogs.
The experiment identified just six atoms of the compound. BhO3Cl proved less volatile than TcO3Cl and ReO3Cl, following the trend expected down group 7. That makes bohrium one of the best-confirmed examples of the periodic table holding up deep into superheavy territory. Its isotopes are short-lived: the longest-lived known ones, made in hot fusion reactions or as decay products, last on the order of a minute.
Discovery
Peter Armbruster and Gottfried Münzenberg's team at GSI in Darmstadt made bohrium in 1981 by bombarding bismuth-209 with chromium-54 and identified bohrium-262 by its decay chain. Dubna had reported a weaker claim in 1976. GSI proposed nielsbohrium, symbol Ns, for Niels Bohr, the Danish physicist who explained the structure of the atom. IUPAC shortened it to bohrium in 1997, to match how other elements honor people by surname.
- Where it’s found
- Bohrium does not occur in nature; it is made in accelerators by fusing medium-mass ions with bismuth or lighter ions with berkelium.
- What it’s used for
- Group 7 chemistry studies
- Testing periodic predictions
- Cold-fusion research
- Nuclear structure research
- In living things
- Bohrium has no biological role; it is radioactive and exists only as individual atoms.
- Safety
- Radioactive and made only a few atoms at a time; it decays within seconds to minutes.
How it compares
Where Bohrium sits among all 118 elements on the trends that shape the table.
- ElectronegativityNo data
Not measured for this element
- Ionization energyNo data
Not measured for this element
- Atomic radiusNo data
Not measured for this element
- Electron affinityNo data
Not measured for this element
- Density37.1g/cm³
#3 of 114 elements with data · predicted
- Melting pointNo data
Not measured for this element
- Density
- 37.1 g/cm³
- Atomic radius
- —
- Covalent radius
- —
- Molar heat
- —
- Appearance
- —
- Discovered by
- Gesellschaft für Schwerionenforschung
Inside the atom
107 electrons arranged in 7 shells: 2 · 8 · 18 · 32 · 32 · 13 · 2.
Orbital diagram
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d5 · shorthand *[Rn] 5f14 6d5 7s2
- 1s2
- 2s2
- 2p6
- 3s2
- 3p6
- 4s2
- 3d10
- 4p6
- 5s2
- 4d10
- 5p6
- 6s2
- 4f14
- 5d10
- 6p6
- 7s2
- 5f14
- 6d5
Each box is an orbital holding up to two electrons of opposite spin. Highlighted subshells hold the valence electrons that decide how Bohrium bonds.
Signature reactions
How the first atoms were made, and how they fall apart.
Nuclear · Cold fusion
GSI cold-fusion synthesis
A chromium-54 nucleus fuses with bismuth-209 and the compound nucleus emits just one neutron. GSI's velocity filter SHIP separated the rare product atoms from the intense beam before they reached the detector.
Conditions: chromium-54 beam on bismuth-209, GSI UNILAC, 1981
Nuclear · Alpha decay
Alpha decay of bohrium-262
Bohrium-262 emits an alpha particle to become dubnium-258, which itself decays further. Following this chain to known nuclides was GSI's proof that element 107 had formed.
Conditions: spontaneous, half-life about 0.1 seconds
Synthesis · Gas-phase oxidation
Formation of bohrium oxychloride
Bohrium-267 atoms made from berkelium-249 and neon-22 reacted in a stream of hydrogen chloride and oxygen to form BhO3Cl, the +7 oxychloride. Its measured volatility fit the trend of TcO3Cl and ReO3Cl, confirming bohrium's place in group 7.
Conditions: single atoms in HCl/O2 carrier gas, Paul Scherrer Institute, 2000
Where you’ll meet it
Niels Bohr
The Danish physicist who explained electron shells is honored by element 107.
Photo: Wikimedia Commons
Bohr model
Bohr's 1913 model of electrons in fixed orbits underlies how chemists still picture atoms like bohrium.
Photo: Wikimedia Commons
GSI Helmholtz Centre for Heavy Ion Research
Bohrium was the first of six elements discovered at GSI in Darmstadt.
Photo: Wikimedia Commons
Rhenium
Rhenium, directly above bohrium in group 7, was the reference for its oxychloride chemistry.
Photo: Wikimedia Commons
Research
No research on Bohrium yet
When Bhavya publishes a project that studies Bohrium, it will be linked here.