Roentgenium

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Roentgenium ( German also Roentgenium ) is an artificially produced chemical element with the element symbol Rg and atomic number 111, which is one of the Transactinoiden. Until now, there was a total of five times produced by different research teams in Darmstadt, Germany and Japan.

History

Roentgenium was first produced on 8 December 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 accelerated to high speeds and then shot at bismuth - through nuclear fusion was the new element Roentgenium, which could be isolated using the velocity filter SHIP and demonstrated a

First it was the provisional name " Unununium " (symbol " Uuu " ), which refers to the three ones of the atomic number. On 18 May 2004, the GSI suggested to name it after the German physicist Wilhelm Conrad Röntgen. The official designation by the IUPAC took place on 1 November 2004, but was - to commemorate the discovery of X- rays on November 8, 1895 - announced to the public only on 8 November 2004.

Properties

On the characteristics of the 111th element is not enough awareness. So far, only five isotopes were detected, all five are alpha emitters. The first detected isotope 272Rg has a half-life of about 2 milliseconds. The longest-lived is 280Rg, which decays with a half-life of 3.6 seconds. The three other known isotopes have half-lives of 4 milliseconds ( 278Rg ), 34.3 milliseconds ( 274Rg ) and 170 milliseconds ( 279Rg ).

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

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

Safety

Classifications according to the Hazardous Substances Ordinance are not available because they only include the chemical danger and play a very minor role compared to the risks based on the radioactivity. Even the latter applies only if there is a relevant material for this amount.