Roentgenium

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111 darmstadtium ← roentgenium → ununbium Au ↑ Rg ↓ (Uhu) Image:Rg-TableImage.png Periodic Table - Extended Periodic Table
General
Name, Symbol, Number	roentgenium, Rg, 111
Chemical series	transition metals
Group, Period, Block	11, 7, d
Appearance	unknown, probably yellow or orange metallic
Standard atomic weight	284 g·mol−1
Electron configuration	perhaps [Rn] 5f14 6d10 7s1 (guess based on gold)
Electrons per shell	2, 8, 18, 32, 32, 18, 1
Phase	presumably a solid
CAS registry number	54386-24-2
Selected isotopes
Main article: Isotopes of roentgenium iso NA half-life DM DE (MeV) DP 280Rg syn 3.6 s
References

Roentgenium (pronounced /rɛntˈgɛniəm/, /rəntˈjɛniəm/, formerly Unununium /ˌjuːnəˈnʌniəm/) is a chemical element in the periodic table that has the symbol Rg and atomic number 111, making it one of the super-heavy atoms. It is a synthetic element whose longest-lived isotope has a mass of 280 and a half-life of 3.6 seconds. Due to its presence in Group 11, it is a transition metal.

Contents 1 History 2 Isotopes 3 See also 4 External links

[edit] History

It was discovered by Peter Armbruster, Gottfried Münzenber, and their team working at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany on December 8, 1994. Only three atoms of it were observed (all ²⁷²Rg), by the fusion of ²⁰⁹Bismuth and ⁶⁴Nickel in a linear accelerator (Nickel was bombarded onto the bismuth target):

<math>\,^{209}_{83}\mathrm{Bi} + \,^{64}_{28}\mathrm{Ni} \, \to \,^{272}_{111}\mathrm{Rg} + \; ^1_0\mathrm{n} \; </math>

The name roentgenium was accepted as a permanent name on November 1 2004 in honor of Wilhelm Conrad Röntgen; before this date, the element was known under the temporary IUPAC systematic element name unununium, symbol Uuu). Some research has referred to it as eka-gold.

[edit] Isotopes

Twelve isotopes of roentgenium are known. The longest-lived of these is ²⁸⁰Rg, which decays through alpha decay and has a half-life of 3.6 seconds. The shortest-lived isotope is ²⁷²Rg, which decays through alpha decay and has a half life of 1.5 ms. Another known isotope, ²⁷⁹Rg, decays through alpha decay and has a half-life of 170 ms.

[edit] See also

• Island of stability

[edit] External links

• WebElements.com - Roentgenium
• IUPAC: Proposal of name roentgenium for element 111
• IUPAC: Element 111 is named roentgenium
• Apsidium - Roentgenium Element 111
• Unununium Element At Chemicalelements.comar:روينتجينيوم

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