Roentgenium
Transition metal (predicted) · Period 7 · Group 11 · d-block
Gold's heavy cousin, named for the discoverer of X-rays
- Atomic mass
- 282 u
- State at 25 °C
- Solid
- Electronegativity
- —
- Melting point
- —
- Boiling point
- —
- Configuration
- *[Rn] 5f14 6d10 7s1
Nucleus drawn at reduced count for clarity. Drag to rotate.
Roentgenium, explained
Video lesson in production
Bhavya’s explainer for this element will play here.
Overview
Roentgenium sits in group 11 beneath copper, silver and gold. Gold's color and chemistry are already shaped by relativistic effects, and in roentgenium those effects are predicted to be much stronger. Calculations suggest a ground-state configuration of 6d9 7s2 instead of gold's 5d10 6s1, because the 7s orbital is so strongly contracted and stabilized that it fills before the 6d shell is complete.
As a result roentgenium is predicted to behave more like a heavy transition metal than a coinage metal, with +3 as its most stable oxidation state, and to look silvery rather than golden. None of this has been tested. Roentgenium-282, the longest-lived known isotope, has a half-life of roughly two minutes, but it is made only as a decay product of heavier elements, at a rate far too low for chemistry so far.
Discovery
Sigurd Hofmann's team at GSI in Darmstadt made roentgenium on 8 December 1994 by bombarding bismuth-209 with nickel-64, detecting three atoms of roentgenium-272. IUPAC recognized the discovery in 2003, and RIKEN in Japan confirmed it independently in 2004. The name, approved in 2004, honors Wilhelm Conrad Röntgen, who discovered X-rays in 1895 and received the first Nobel Prize in Physics in 1901.
- Where it’s found
- Roentgenium does not occur in nature; it is made in accelerators or appears in the decay chains of nihonium, moscovium and tennessine.
- What it’s used for
- Relativistic effects research
- Testing group 11 predictions
- Decay-chain identification
- Nuclear structure research
- In living things
- Roentgenium has no biological role; it is radioactive and has only ever existed as individual atoms.
- Safety
- Radioactive and made only a few atoms ever; it decays within seconds to minutes.
How it compares
Where Roentgenium 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 affinity151kJ/mol
#13 of 109 elements with data · predicted
- Density28.7g/cm³
#7 of 114 elements with data · predicted
- Melting pointNo data
Not measured for this element
- Density
- 28.7 g/cm³
- Atomic radius
- —
- Covalent radius
- —
- Molar heat
- —
- Appearance
- —
- Discovered by
- Gesellschaft für Schwerionenforschung
Inside the atom
111 electrons arranged in 7 shells: 2 · 8 · 18 · 32 · 32 · 17 · 2.
Orbital diagram
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d9 · shorthand *[Rn] 5f14 6d10 7s1
- 1s2
- 2s2
- 2p6
- 3s2
- 3p6
- 4s2
- 3d10
- 4p6
- 5s2
- 4d10
- 5p6
- 6s2
- 4f14
- 5d10
- 6p6
- 7s2
- 5f14
- 6d9
Each box is an orbital holding up to two electrons of opposite spin. Highlighted subshells hold the valence electrons that decide how Roentgenium bonds.
Signature reactions
How the first atoms were made, and how they fall apart.
Nuclear · Cold fusion
GSI cold-fusion synthesis
Nickel-64 fuses with bismuth-209 and the compound nucleus emits one neutron. Three atoms were detected over weeks of bombardment and identified through their decay chains.
Conditions: nickel-64 beam on bismuth-209, GSI UNILAC, 1994
Nuclear · Alpha decay
Alpha decay of roentgenium-272
Roentgenium-272 emits an alpha particle to become meitnerium-268, which decays in turn to bohrium and dubnium. That chain was the fingerprint for element 111.
Conditions: spontaneous, half-life a few milliseconds
Where you’ll meet it
Wilhelm Röntgen
The German physicist who discovered X-rays is honored by element 111.
Photo: Wikimedia Commons
X-ray
Röntgen's 1895 discovery transformed medicine and gave element 111 its namesake.
Photo: Wikimedia Commons
Gold
Gold sits directly above roentgenium, but relativistic effects are predicted to make the two quite different.
Photo: Wikimedia Commons
GSI Helmholtz Centre for Heavy Ion Research
GSI made roentgenium in 1994, weeks after darmstadtium.
Photo: Wikimedia Commons
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Research
No research on Roentgenium yet
When Bhavya publishes a project that studies Roentgenium, it will be linked here.