What is Roentgenium

A synthetic radioactive element, roentgenium (pronounced as runt-GEN-ee-əm), also known as unununium, is denoted by the symbol Rg ^{[1, 2]}. It is not found naturally and is only produced in the lab under controlled circumstances.

History of Roentgenium

How did the Element get its Name

It is named after Wilhelm Conrad Röentgen, the German physicist and mechanical engineer who first observed X-ray beams ^{[1, 2]}.

When was Roentgenium Discovered

In 1994, at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, Peter Armbruster, Gottfried Münzenber and their team bombarded atoms of bismuth-209 with ions of nickel-64 using a linear accelerator to produce three atoms of roentgenium-272, having a half-life of 1.5 milliseconds, along with a free neutron ^{[1, 2]}.

Although seven isotopes of the metal have been synthesized so far, roentgenium-281 is the most stable one with a half-life of 26 seconds after which it decays to meitnerium-276 through spontaneous fission ^{[1, 2, 7]}.

Classification and Position of Roentgenium in the Periodic Table ^{[1, 2, 4]}

Element Category (Family)	Transition Metal
Group	11
Period	7
Block	D

Roentgenium Properties

General Properties
Atomic Weight	281
Average Atomic Mass	272
Physical Properties [2, 7, 9]
Color	Metallic orange (unconfirmed)
Odor	Unknown
Melting Point	Unknown
Boiling Point	Unknown
Freezing Point	Unknown
Density (g/cm3)	28.7 (unconfirmed)
State of Matter at Room Temperature	Solid (unconfirmed)
Malleability	Unknown
Hardness	Unknown
Electrical Conductivity	Unknown
Roentgenium Chemical Properties [4]
Flammability	Unknown
Radioactivity	Unknown
Oxidation state/Oxidation number	[-1], [+1], [+3], [+5]

Atomic data of Roentgenium ^{[2, 4, 5]}

Atomic Number	111
Valence Electrons	6d107s1
Electron Configuration	[Rn] 5f146d107s1
Atomic Structure
-Number of Electrons	111
-Number of Protons	111
-Number of Neutrons	170
Radius of Atom
-Atomic Radius	114
-Covalent Radius ((Å))	1.21
Electron Affinity	Unknown
Electronegativity	Unknown
Ionization Energy	Unknown

What is Roentgenium Used for

Since it is not found in the environment and is also quite unstable, there are no industrial applications other than being used for basic scientific research. As only a few atoms of the element have been produced, its reactivity with other elements and compounds is unknown ^[6].

Can the Element be Dangerous

Although the short half-life of Rg does not provide much scope to study its effects on the environment and health, it may be toxic due to its radioactivity when produced in more significant amounts ^[7].

Interesting Facts

• Rg is believed to exhibit properties similar to gold, silver, ruthenium, and platinum. It even looks somewhat like gold ^{[6, 7]}
• In 1986, some physicists at the Russian Joint Institute for Nuclear Research (JINR) had attempted to produce element 111 by bombarding bismuth with nickel but were unable to detect any atoms ^[2]
• The element is classified as super heavy since it has an atomic number higher than 105 ^[7]
• The part of the electronic configuration of roentgenium that is equivalent to the noble gas of the preceding period is abbreviated as [Rn] ^[8]

Roentgenium Cost

The short half-life of the metal does not make it commercially available even today.

References
1. https://education.jlab.org/itselemental/ele111.html
2. http://www.rsc.org/periodic-table/element/111/roentgenium
3. https://www.livescience.com/41347-facts-about-roentgenium.html
4. https://www.chemicool.com/elements/roentgenium.html
5. http://www.chemistry.patent-invent.com/chemistry/elements/roentgenium.html
6. https://www.webelements.com/roentgenium/chemistry.html
7. http://www.elementsdatabase.com/Roentgenium-Rg-111-element/
8. https://www.schoolmykids.com/learn/interactive-periodic-table/rg-roentgenium
9. https://environmentalchemistry.com/yogi/periodic/mass.html