Bohrium (Bh)

In 2000 a team produced six atoms of bohrium-267, one at a time, and passed each through a column of quartz to see what it would stick to — the atoms formed a volatile oxychloride and travelled exactly as technetium and rhenium do, confirming bohrium as a group 7 element. That is what chemistry looks like at this end of the table: six atoms, a chromatography column, and a decay signature to prove which atom went where. GSI originally proposed nielsbohrium, since IUPAC then discouraged using surnames alone.

Properties

Atomic number

107

Symbol

Bh

Mass number of most stable isotope

[270]

Category

Transition metal

Group

7

Period

7

Block

d-block

Electron configuration

[Rn] 7s² 5f¹⁴ 6d⁵

Electrons per shell

2, 8, 18, 32, 32, 13, 2

Oxidation states

+7, +5, +4, +3

Discovered

1981 by Peter Armbruster, Gottfried Münzenberg and colleagues at GSI Darmstadt

Electron configuration

Full

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d⁵

Noble gas shorthand

[Rn] 7s² 5f¹⁴ 6d⁵

Shells

K: 2 · L: 8 · M: 18 · N: 32 · O: 32 · P: 13 · Q: 2

What it is used for

• Research only; no application outside the laboratory

Hazards

• Intensely radioactive; exists only as individual atoms in an accelerator

Melting point, boiling point, density and electronegativity are omitted: no measurement is possible. The mass given is the mass number of bohrium-270, the longest-lived at roughly a minute.

Several physical properties are not listed for bohrium because no bulk sample has ever existed. Only a handful of atoms have been produced, often with half-lives measured in seconds, so published melting points and densities for elements in this range are calculations rather than measurements. They are omitted rather than presented as observed values.

Neighbours in the table

Group 7

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Bohrium sits in group 7 with manganese, technetium, rhenium.