# Roentgenium

properties
[ Rn ] 5 f 14 6 d 10 7 s 1 (?)
111 Rg
General
Name , symbol , atomic number Roentgenium, Rg, 111
Element category
Group , period , block 11 , 7 , d
CAS number 54386-24-2
Atomic
Atomic mass 280 u
Electron configuration [ Rn ] 5 f 14 6 d 10 7 s 1 (?)
1. Ionization energy 1 023 kJ / mol
Physically
Isotopes
isotope NH t 1/2 ZA ZE (M eV ) ZP
272 Rg {syn.} 3.8 ms α 11.44 268 Mt
274 Rg {syn.} 6.4 ms α 11.6 270 Mt
278 Rg {syn.} 4.2 ms α 10.7 274 m
279 Rg {syn.} 170 ms α 10.5 275 mt
280 Rg {syn.} 3.6 s α 10.0 276 Mt
For other isotopes see list of isotopes
Hazard and safety information

GHS hazard labeling
no classification available
As far as possible and customary, SI units are used.
Unless otherwise noted, the data given apply to standard conditions .

Roentgenium (English name; German name: Röntgenium ) is an artificially created chemical element with the element symbol Rg and the atomic number 111, which belongs to the transactinoids . In the periodic table of the elements it is in the 11th  IUPAC group , the copper group . So far it has been produced a total of five times by different research teams in Darmstadt and Japan .

## history

Photo background for the presentation of Roentgenium at GSI

Roentgenium was first produced on December 8, 1994 at the Society for Heavy Ion Research (GSI) in Darmstadt by an international research team led by Sigurd Hofmann . With the help of the particle accelerator UNILAC , nickel atoms were brought to high speeds and then shot at bismuth atoms - the new element Roentgenium was created through nuclear fusion , which could be isolated and detected with the help of the SHIP speed filter :

${\ displaystyle \ mathrm {^ {64} _ {28} Ni \ + \ _ {\ 83} ^ {209} Bi \ \ longrightarrow \ _ {111} ^ {272} Rg \ + \ _ {0} ^ { 1} n}}$

First the element was given the systematic name Unununium (chemical symbol Uuu ), from the Latin unum for 'one', which denotes the three ones of the atomic number. On May 18, 2004, the GSI suggested that it be named after the German physicist Wilhelm Conrad Röntgen . The official designation by the IUPAC took place on November 1, 2004, but - to commemorate the discovery of X-rays on November 8, 1895 - was not announced to the public until November 8, 2004.

## properties

Little is known about the properties of the 111th element. So far only five isotopes have been detected, all five are alpha emitters . The first detected isotope 272 Rg has a half-life of about 2 milliseconds . The longest-lived is 280 Rg, which decays with a half-life of 3.6 seconds. The other three known isotopes have half-lives of 4 milliseconds ( 278 Rg), 34.3 milliseconds ( 274 Rg) and 170 milliseconds ( 279 Rg), respectively .

Similar to the lighter homologue gold , strong relativistic effects are assumed in theoretical calculations . The Rg + ion is therefore possibly the softest ion in aqueous solution according to the HSAB concept . An experimental verification is difficult due to the short half-lives.

The electron affinity was calculated to be 1.56 eV and the ionization energy to be 10.6 eV.

## safety instructions

There is no classification according to the CLP regulation or other regulations, because only a few atoms of this element can be produced at the same time and thus far too few for chemical or physical hazard.

Commons : Roentgenium  - collection of images, videos and audio files
Wiktionary: Roentgenium  - explanations of meanings, word origins, synonyms, translations

## Individual evidence

1. Entry on roentgenium at WebElements, https://www.webelements.com , accessed on June 13, 2020.
2. The hazards emanating from radioactivity do not belong to the properties to be classified according to the GHS labeling. With regard to other hazards, this element has either not yet been classified or a reliable and citable source has not yet been found.
3. ^ Lars Röglin: Roentgenium. In: PSE online - The Periodic Table of the Elements on the WWW. Material-Verlag, accessed on August 19, 2018 .
4. a b Chemical element 111 is called "Roentgenium". In: gsi.de. GSI Helmholtz Center for Heavy Ion Research , August 11, 2004, accessed on August 19, 2018 .
5. ^ Sigurd Hofmann , Victor Ninov , FP Heßberger, Peter Armbruster , H. Folger, Gottfried Münzenberg , HJ Schött, AG Popeko, AV Yeremin, AN Andreyev, S. Saro, R. Janik, M. Leino: The new element 111 . In: Journal of Physics A Hadrons and Nuclei . tape 350 , no. 4 , December 1995, pp. 281–282 , doi : 10.1007 / BF01291182 (English, available online as a preprint from cds.cern.ch [PDF; 179 kB ]).
6. ^ PJ Karol, H. Nakahara, BW Petley, E. Vogt: On the Claims for Discovery of Elements 110, 111, 112, 114, 116, and 118 (IUPAC Technical Report) . In: Pure and Applied Chemistry . tape 75 , no. 10 , October 2003, p. 1601-1611 , doi : 10.1351 / pac200375101601 (English).
7. ^ John Corish, GM Rosenblatt: Name and symbol of the element with atomic number 111 (IUPAC Recommendations 2004) . In: Pure and Applied Chemistry . tape 76 , no. December 12 , 2004, pp. 2101-2103 , doi : 10.1351 / pac200476122101 (English).
8. ^ Norman E. Holden: 2007 Nuclear Data Review . Contribution to the 13th International Symposium on Reactor Dosimetry, Alkmaar (Netherlands). Brookhaven National Laboratory , May 2008, Data on the Very Heavy Chemical Elements, pp. 5 (English, bnl.gov [PDF; 188 kB ]).
9. Kosuke Morita: Experiments on searching for the heaviest elements . In: Nuclear Physics A . tape 805 , no. 1–4 , June 1, 2008, pp. 172c – 179c , doi : 10.1016 / j.nuclphysa.2008.02.238 (English).
10. ^ Robert D. Hancock, Libero J. Bartolotti, Nikolas Kaltsoyannis: Density Functional Theory-Based Prediction of Some Aqueous-Phase Chemistry of Superheavy Element 111. Roentgenium (I) Is the "Softest" Metal Ion . In: Inorganic Chemistry . tape 45 , no. 26 , December 25, 2006, pp. 10780-10785 , doi : 10.1021 / ic061282s (English).
11. Ephraim Eliav, Uzi Kaldor, Peter Schwerdtfeger, Bernd A. Hess, Yasuyuki Ishikawa: Ground State Electron Configuration of Element 111 . In: Physical Review Letters . tape 73 , no. December 24 , 1994, pp. 3203–3206 , doi : 10.1103 / PhysRevLett.73.3203 (English, freely available online through researchgate.net ).