107BhBohrium[270]

A real sample of the element Bohrium — Synthetic element — no real sample has ever been photographed

Bohrium (Bh)

“Named for Niels Bohr, master of the atom — its discovery at Darmstadt in 1981 rested on just a handful of atoms.”

View group 7 →View period 7 →See in trends →

Atomic number107

Atomic mass[270]

Group7

Period7

BlockD-block

PhaseSolid

Electron structure

How its electrons are arranged

[Rn] 5f¹⁴ 6d⁵ 7s²

Shell 1

2e⁻

Shell 2

8e⁻

Shell 3

18e⁻

Shell 4

32e⁻

Shell 5

32e⁻

Shell 6

13e⁻

Shell 7

2e⁻

Computed from the aufbau principle, with known real-world exceptions applied automatically.

🎯 Exam focus

Questions to practise

Try each question yourself first — then open it to read the full model answer.

1At which German research centre and in which year was bohrium first made, and which two nuclei were fused together?

Model answerBohrium was first made in 1981 at the GSI heavy-ion research centre in Darmstadt, Germany. A team led by Peter Armbruster and Gottfried Münzenberg bombarded a bismuth-209 target with chromium-54 ions from the UNILAC accelerator, fusing those two nuclei to make Bh-262, and traced its alpha-decay chain back through known isotopes to prove the discovery.

2What did the volatility of bohrium oxychloride teach chemists about Group 7 trends at the superheavy end of the table?

Model answerGas-phase chemistry on single atoms showed that bohrium’s oxychloride, $\mathrm{BhO_{3}Cl}$ , is volatile in almost exactly the way rhenium’s $\mathrm{ReO_{3}Cl}$ is. That taught chemists a reassuring lesson: even at the superheavy end of the table, where relativistic effects press hard on every bond, the Group 7 family trend still holds — just barely — and the periodic law keeps its grip.

3Which atomic model from your chemistry syllabus carries the same scientist’s name as element 107?

Model answerBohr’s shell model of the atom — the picture of electrons circling the nucleus in fixed shells that hangs on classroom walls and opens the atomic-structure chapter of the NCTB syllabus. It carries the name of Niels Bohr, the Danish physicist who first described those fixed shells, and element 107, bohrium, honours exactly the same scientist.

4Why must bohrium experiments be automated to finish within about a minute of each atom’s birth?

Model answerBecause even bohrium’s longest-lived isotope, Bh-270, survives only about a minute, and the element is made one atom at a time. Human hands cannot separate, purify and measure a lone radioactive atom in so little time, so detection, chemistry and data-taking must all run automatically, almost in the same instant the atom is born.

5Give bohrium’s group, period and block, and name its two lighter Group 7 chemical cousins.

Model answerBohrium sits in Group 7, Period 7, among the d-block transition metals, because its differentiating electron enters the 6d subshell. Its two lighter Group 7 cousins are technetium and rhenium; bohrium is their superheavy relative, predicted to be a heavy silvery metal built in rhenium’s image.

6The discoverers first proposed “nielsbohrium” — what did IUPAC change the name to, and which physicist was being honoured?

Model answerIUPAC trimmed the discoverers’ proposal to bohrium in 1997, keeping the honour but shortening the name. The physicist being honoured is Niels Bohr of Denmark, master of the atom, who first described electrons occupying fixed shells — so element 107 carries his name into Period 7, and every classroom chart of Bohr’s model quietly salutes the same man.

Quick answers

One fact, one page

Every key fact of this element has its own clean page — a direct two-line answer first, then the working. Fast to load, easy to share.

Electron configurationThe full arrangement, step by step ValencyHow many bonds it forms Atomic massThe standard weight, explained Metal or nonmetalWhich family it belongs to Everyday usesWhere you meet it daily

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Study

The notes

About the element

Characteristics

A synthetic Group 7 transition metal — the superheavy relative of technetium and rhenium — made only one atom at a time.
Even its longest-lived isotope Bh-270 lasts only about a minute, so experimenters must work almost instantaneously.
Gas-phase chemistry showed its oxychloride $\mathrm{BhO_{3}Cl}$ is volatile like rhenium’s $\mathrm{ReO_{3}Cl}$ — the family trend holds, just barely.
Like everything beyond element 104, its electrons race at relativistic speeds, subtly reshaping its chemical bonds.

Appearance

Bohrium has never been seen — only counted, atom by atom, through its decay flashes. It should be a heavy, silvery Group 7 transition metal beneath rhenium and technetium, with properties bent by the relativistic effects that grow extreme this far down the table.

Real world

Where you meet it

✦ Uses

Verifying Period 7’s vertical trends: comparing volatile $\mathrm{BhO_{3}Cl}$ with $\mathrm{ReO_{3}Cl}$ tests how relativity presses on Group 7 chemistry.
Decay-chain anchoring: bohrium’s known alpha energies serve as signposts when still-heavier elements are being identified.
Pushing one-atom-at-a-time chemical methods to their limit — the faster, hotter separations pioneered for Bh guide later work.

◍ Everyday examples

NCTB chemistry introduces Bohr’s shell model of the atom — the same physicist whose name element 107 carries into Period 7.
The wall chart of Bohr’s atomic model hanging in your classroom quietly salutes element 107 as well.

Story

History & name

In 1981 a team at the GSI heavy-ion research centre in Darmstadt, Germany, led by Peter Armbruster and Gottfried Münzenberg, bombarded bismuth-209 with chromium-54 ions from the UNILAC accelerator and traced the alpha-decay chain of Bh-262 back through known isotopes — the rigorous new method that made their discoveries stick. The discoverers proposed the name nielsbohrium; IUPAC trimmed it to bohrium in 1997, honouring the Danish physicist Niels Bohr.

Name originHonours Niels Bohr, Danish physicist who first described electrons in fixed shells.

Neighbours

Nearby elements

The elements that sit right beside this one on the table — often the closest chemical cousins.

105DbDubnium[268]106SgSeaborgium[269]108HsHassium[269]109MtMeitnerium[278]