Roentgenium (Rg)

Roentgenium is a synthetic chemical element with the atomic number 111 in the periodic table. It’s a synthetically produced transuranium element that cannot be found in Earth’s crust. As a member of the transition metals family of periodic table elements, this noble metal has three valence electrons and is currently used only in scientific research.  

Chemical and Physical Properties of Roentgenium

Symbol in the periodic table of elementsRg
Atomic number111
Atomic weight (mass)[271.8] g.mol-1
Group number11
Period7 (d-block)
ColorPossibly metallic-orange or metallic-yellow
Physical statePossibly solid at room temperature
Half-lifeFrom 2.0(8) milliseconds to 10.7 minutes (?)
Electronegativity according to PaulingUnknown
Melting pointUnknown
Boiling pointUnknown
Van der Waals radiusUnknown
Ionic radiusUnknown
Most characteristic isotope272Rg
Electronic shell[Rn] 7s15f146d10
The energy of the first ionizationN/A
The energy of the second ionizationN/A
Discovery dateIn 1994 by Peter Armbruster, Gottfried Münzenberg, and Sigurd Hofmann

Located between the elements darmstadtium and copernicium, roentgenium has the periodic table symbol Rg, atomic number 111, predicted atomic mass of [271.8] g.mol-1, and electron configuration [Rn] 7s15f146d10 in the periodic table. This chemical element is predicted to belong to the transition metals family of the periodic table. 

Following the chemical calculations, element 111 is assumed to be a ductile and malleable noble metal whose chemical properties resemble the ones of metals classified in the groups VIIb, VIII, and Ib, such as rhenium, ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold. According to the chemical calculations, the atomic radius of roentgenium is expected to be around 138 pm.

It’s assumed that roentgenium could mostly resemble the element gold (Ag). In that case, element 111 could easily form acids and chlorides. Also, this noble metal could be characterized by excellent electrical and thermal conductivity, as well as strong anti-corrosive properties.

How Was Roentgenium Discovered?

It took more than eight years of scientific trials and errors and two teams of distinguished discoverers for element 111 to be produced.

The first attempt to discover this transuranium element was made by the nuclear physicists at the Joint Institute of Nuclear Research at Dubna, Russia. In 1886, the Russian team attempted to produce the element unununium (Uuu) by a bombardment of bismuth atoms with nickel in a linear accelerator. Despite their efforts and experience, their experiment gave no new element.

In 1994, the team of scientists led by the German nuclear physicists Gottfried Munzenberg, Peter Armbruster, and Sigurd Hofmann attempted a similar method for the production of element 111. At the Gesellschaft für Schwerionenforschung (GSI Helmholtz Centre for Heavy Ion Research) in Darmstadt, Germany, they carried out an experiment that included a similar method that was previously used by the Russian team of researchers. 

Namely, Munzenberg, Armbruster, and Hofmann also employed bombardment of a bismuth-209 target with nickel-64 ions in a heavy-ion accelerator. By this, the team tried to fuse the two nuclei and thus form a bigger atom. This time, the experiment brought revolutionary success to the Darmstadt team of discoverers by producing a new element with 111 protons and neutrons, i.e. roentgenium (111Rg). The first isotope of roentgenium produced by the German team was roentgenium-272 that decayed after 1.5 milliseconds into atoms of meitnerium-268 by emitting an alpha particle. 

How Did Roentgenium Get Its Name?

The name roentgenium (Rg) was proposed by the GSI team. In this way, the team of discoverers behind element 111 wanted to honor the German mechanical engineer and physicist Wilhelm Conrad Röntgen (also: Wilhelm Conrad Roentgen, 1845-1923) and his contribution to modern physics and the discovery of the X-radiation phenomenon. 

In 1901, Wilhelm Röntgen won the first Nobel Prize in Physics for his discovery of X-rays, which is both a revolutionary and indispensable method of diagnostics in medicine even nowadays. 

Where Can You Find Roentgenium?

Since this transuranium element is a synthetically produced radioactive substance, it does not occur in nature. Roentgenium can be found only in a strictly controlled environment of a nuclear laboratory. 

Roentgenium in Everyday Life

There are only a few atoms produced of this radioactive element. For this, roentgenium is applied only in chemical experimentation and scientific research projects. Since it has 111 protons and neutrons, this super-heavy transuranium element is also used for synthetisation of other man-made chemical elements.

How Dangerous Is Roentgenium?

If there were larger concentrations of roentgenium produced, this chemical element would have been considered as highly toxic and dangerous due to its radioactivity. 

Environmental Effects of Roentgenium

Roentgenium does not occur freely in nature and it doesn’t have a biological role in the environment. In addition, isotopes of this radioactive metal are so short-lived that its effect on the environment cannot be considered. 

Isotopes of Roentgenium

There are 9 observed isotopes of element 111, with atomic masses ranging from  272Rg to 286Rg. Being highly radioactive, this chemical element has no stable isotopes. 

Roentgenium-272 was the first form of this transuranium element that was produced by direct synthetisation. The remaining roentgenium isotopes are decay products of the elements nihonium, moscovium, tennessine, copernicium, flerovium, and livermorium that undergo alpha decay and spontaneous fission. 

NuclideZNIsotopic mass (Da)[n 1][n 2]Half-lifeDecaymode[n 3]DaughterisotopeSpin andparity[n 4]
272Rg111161272.15327(25)#2.0(8) ms[3.8(+14−8) ms]α268Mt5+#, 6+#
274Rg[n 5]111163274.15525(19)#6.4(+307−29) msα270Mt
278Rg[n 6]111167278.16149(38)#4.2(+75−17) msα274Mt
279Rg[n 7]111168279.16272(51)#0.17(+81−8) sα275Mt
280Rg[n 8]111169280.16514(61)#3.6(+43−13) sα (87%)276Mt
EC (13%)[6]280Ds
281Rg[n 9]111170281.16636(89)#17 (+6−3) s[2]SF (90%)(various)
α (10%)277Mt[2]
282Rg[n 10]111171282.16912(72)#2.1 (+1.4-0.6) min[7]α278Mt
283Rg[n 11]111172283.17054(79)#5.1 min?SF(various)
286Rg[n 12]11117510.7 min?α282Mt

Source: Wikipedia

List of Roentgenium Compounds

Due to the limited quantities and the expensive process of synthesization of this chemical element, most of its physical and chemical properties, as well as the compounds of roentgenium cannot be calculated. 

5 Interesting Facts and Explanations

  1. The temporary name of element 111 was ‘unununium’, meaning ‘one-one-one’ in Latin. It had the symbol ‘Uuu’. 
  2. On November 1st, 2004, the suggested name roentgenium for element 111 was approved as a permanent name by the Joint Working Party of the International Union of Pure and Applied Chemistry (IUPAC).
  3. The roentgen (or röntgen) is a unit of measurement for the exposure of X-rays and gamma rays. This measuring unit was also named after the great German physicist and discoverer. 
  4. Roentgenium is classified as a d-block element in the periodic table, alongside the chemicals bohrium, niobium, manganese, chromium, and vanadium.
  5. Armbruster and Munzenberg participated in the discovery of all transuranium elements from 107 to 112. 

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