Roentgenium was produced by bombarding bismuth with nickel nuclei at GSI. It is a radioactive element studied in extremely small quantities. Its location below gold on the table is useful for organizing questions, but it should not be read as evidence for a measured color or familiar metallic object.
FROM ELEMENT TO APPLICATION
AN ELEMENT IN CONTEXT
Why does independent repetition strengthen a roentgenium nuclear assignment?
Roentgenium isotopes in decay experiments
FOLLOW THIS RELATIONSHIP
Establish the original evidence
An initial production experiment links detector events to a proposed roentgenium nucleus. Treat that sequence as an identification argument whose individual observations and interpretation can be examined.
Explore the model (optional)
RgFORM → INTERACTION → CONSEQUENCE
Follow the explanation in either direction. These are authored steps, not a physical clock.
Optional: check your understanding
USE THE EXPLANATION
Which development adds experimental support to an initial assignment?
Atomic identity, reference properties and structure models
INTERACTIVE 3D111 visible sites
An electron censusDrag to rotate · scroll or pinch to zoom
[Rn] 5f14 6d10 7s1. Grouping electrons by principal shell connects the neutral-atom configuration to periodic-table patterns.
What this representation means
A three-dimensional counting diagram. Dots are count markers, not measured electron positions; spherical placement and spacing are arbitrary. There are no electron trajectories here. Orbitals describe quantum states.
For superheavy elements, this configuration is a theoretical assignment. It does not establish measured bulk chemistry or a material state.
Loading reference properties…
HISTORY & HUMAN DISCOVERY
Röntgen’s name attached to nuclear evidence
Roentgenium was discovered at GSI in December 1994, soon after darmstadtium. Its name, approved in 2004, honors Wilhelm Conrad Röntgen and his discovery of X-rays. That tribute should not be confused with the experimental method used to identify element 111: the crucial evidence came from nuclear production and observations. The story demonstrates how an element’s namesake and the element’s own scientific properties can belong to different chapters of physics.
1994
Discovery
GSI reports element 111 from nuclear experiments.
2004
Name approved
Roentgenium, Rg, is adopted in honor of Wilhelm Röntgen.
Roentgenium is made artificially and detected in extremely small numbers of radioactive atoms. There is no established natural or ordinary material supply. It may be investigated through direct production or as part of heavier decay sequences, with the assignment built from nuclear evidence rather than a visible specimen.
The configuration follows RSC’s predicted neutral-atom notation; alternative theoretical assignments exist, so it is not a measured ground-state map. Roentgenium sits below gold in group 11, but its compound chemistry and bulk material properties are not established experimentally. Relativistic calculations explore how its bonds might differ from those of gold.
Each section links its supporting references. Descriptions and diagrams were authored for this atlas. Source checks completed. Source checks dated 2026-09-06.
CITE THIS PAGE
Family labels and the group-3 layout are teaching conventions. A table position does not establish an unknown bulk property. Electronic configurations refer to neutral atoms; ions and material environments require their own account.
Read each reference property together with its units, conditions and the reference information below.
Not yet recorded: electron affinity, second ionization energy, ground-state term symbol, van der waals radius, thermal conductivity, specific heat capacity, electrical resistivity, crystal structure, lattice parameter a, space group, abundance in seawater, abundance in the universe, annual production, supply-risk listing, hazard classification, biological role, cas registry number, pubchem cid, wikidata item. These families are declared and awaiting an ingestion run against the source each names; they are listed here rather than shown as empty rows.
Physical
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Phase at 20 °C
Not recorded
293.15 K, 101.325 kPa
Melting point
Not recorded
at standard pressure unless noted
Boiling point
Not recorded
101.325 kPa
Density
Not recorded
solids and liquids at 293 K; gases at 273 K and 101.325 kPa
Atomic and electronic
Intended reference: Pauling electronegativity scale · Widely tabulated; original in The Nature of the Chemical Bond
Electronegativity
Not recorded
Pauling scale
First ionization energy
Not recorded
gas-phase neutral atom, ground state
Covalent radius
Not recorded
single-bond covalent radius
Common oxidation states
Not recorded
states met in ordinary compounds; not exhaustive
Occurrence and identity
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Abundance in the crust
Not recorded
upper continental crust, mass fraction
Has stable isotopes
Noderived
Discovery year in CE
1994 CEderived
WHERE IT SITS AMONG ITS NEIGHBORS
Electronegativity across period 7
Ra 0.9 Pauling · Radium
Electronegativity across period 7. Exact values.
Ra
0.9
Ac
1.1
Th
1.3
Pa
1.5
U
1.38
Np
1.36
Pu
1.28
Am
1.13
Cm
1.28
Bk
1.3
Cf
1.3
Es
1.3
Fm
1.3
Md
1.3
No
1.3
Lr
1.3
Electronegativity down group 11
Cu 1.9 Pauling · Copper
Electronegativity down group 11. Exact values.
Cu
1.9
Ag
1.93
Au
2.54
The trend uses the same reference-property values as the periodic table. Elements with no recorded value are left out of the line rather than drawn at zero.
