Roentgenium
Atomic Data
| Atomic Number | 111 |
| Symbol | Rg |
| Atomic Weight | 282 u |
| Density (STP) | N/A |
| Melting Point | N/A °C (None K) |
| Boiling Point | N/A °C (None K) |
| Electronegativity | : |
| Electron Config. | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f14 6s2 6p6 6d9 7s2 |
| Oxidation States | +1, +3 |
| Phase at STP | Solid |
| Category | Transition Metal |
| Period / Group | 7 / 11 |
| CAS Number | 54386-24-2 |
Electron Configuration
[Rn] 5f14 6d9 7s2
| Shell | n | Subshell | Electrons | Cumulative |
|---|---|---|---|---|
| K | 1 | 1s | 2 | 2 |
| L | 2 | 2s | 2 | 4 |
| L | 2 | 2p | 6 | 10 |
| M | 3 | 3s | 2 | 12 |
| M | 3 | 3p | 6 | 18 |
| M | 3 | 3d | 10 | 28 |
| N | 4 | 4s | 2 | 30 |
| N | 4 | 4p | 6 | 36 |
| N | 4 | 4d | 10 | 46 |
| N | 4 | 4f | 14 | 60 |
| O | 5 | 5s | 2 | 62 |
| O | 5 | 5p | 6 | 68 |
| O | 5 | 5d | 10 | 78 |
| O | 5 | 5f | 14 | 92 |
| P | 6 | 6s | 2 | 94 |
| P | 6 | 6p | 6 | 100 |
| P | 6 | 6d | 9 | 109 |
| Q | 7 | 7s | 2 | 111 |
| Total | 111 | 111 | ||
Isotopes of Roentgenium
Roentgenium is monoisotopic: ²⁸²Rg is its only naturally occurring stable isotope, accounting for 100% of all natural Roentgenium.
| Isotope | Symbol | Protons | Neutrons | Abundance | Stability |
|---|---|---|---|---|---|
| Roentgenium-282 | ²⁸²Rg | 111 | 171 | trace | Stable |
Abundance & Occurrence
Roentgenium is present in Earth's crust at approximately trace amounts by mass and at approximately trace amounts by mass throughout the universe.
Earth's Crust (ppm by mass)
Universe (ppm by mass)
Discovery & History
Read more about the discovery of the periodic table of elements →
Safety & Handling
- Alpha radiation and very short half-life: Roentgenium isotopes are alpha emitters with half-lives of seconds or less; Rg-282 (t½ = 100 s) is among the longer-lived, still far too short for conventional chemistry.
- No practical hazard: Only a handful of roentgenium atoms have ever been produced; there is no bulk radiological or chemical hazard from the element itself.
- Accelerator environment: The primary occupational hazard is the radiation environment of the GSI accelerator facility during and after bombardment runs.
- Regulatory controls: All transactinide experiments are conducted at licensed nuclear facilities under comprehensive radiation protection programmes.
Roentgenium in the Real World
Real-World Uses
- Superheavy element nuclear and chemical research: Roentgenium (Rg-280, Rg-282) is a Group 11 element predicted by relativistic theory to deviate substantially from gold chemistry; its 6d¹⁰7s¹ ground state and relativistic stabilisation of the 7s orbital may make it behave more like a Group 11 element with unusual bonding preferences.
- Alpha-decay chain identification: Roentgenium isotopes appear in the decay chains of elements 115 (moscovium) and 119 (predicted), providing identification links in the synthesis and characterisation of superheavy nuclei at Z>111.
- No commercial applications: Roentgenium is produced atom-by-atom; its most stable known isotope has a half-life of less than 30 seconds, and no practical use outside fundamental research is possible.
Downloadable Resources
Free periodic table reference sheets for classrooms, study sessions, and laboratory use.
Frequently Asked Questions
Has roentgenium ever been used for anything?
No. Roentgenium has no practical uses. Its most stable isotope (Rg-282) has a half-life of about 100 seconds. It is produced only a few atoms at a time in particle accelerators and studied solely for fundamental nuclear physics. Due to its very short half-life, no chemical experiments have been performed on roentgenium.
How many atoms of roentgenium have been made?
Roentgenium was first synthesised at GSI Darmstadt in 1994 by bombarding bismuth-209 with nickel-64 ions, producing just a single atom. Since then, only a few dozen atoms of roentgenium have been produced across all experiments worldwide. All decayed within minutes.
Is roentgenium radioactive?
Yes, all isotopes of roentgenium are radioactive. The most stable known, Rg-282, has a half-life of about 100 seconds. It decays by alpha emission. All roentgenium atoms are produced and decay at the single-atom level in particle accelerator experiments.
How did roentgenium get its name?
Roentgenium was named after Wilhelm Röntgen, the German physicist who discovered X-rays in 1895 and received the first Nobel Prize in Physics in 1901. The name was approved by IUPAC in 2004. Like other superheavy elements, roentgenium was known by the placeholder name unununium (Uuu) until the official name was agreed.