Roentgenium (German: [ʁœntˈɡeːni̯ʊm] ⓘ) is a synthetic chemical element; it has symbol Rg and atomic number 111. It is extremely radioactive and can only be created in a laboratory.

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.

Ununium or unununium was a temporary name given to the man made element number 111. Un means one so the original name meant one-one-one. It is found within group 11, period 7 and block d of the periodic table of elements.

Name: Unununium Symbol: Uuu Atomic Number: 111 Atomic Mass: (272.0) amu Melting Point: Unknown Boiling Point: Unknown Number of Protons/Electrons: 111 Number of Neutrons: 161 Classification: Transition Metal Crystal Structure: Unknown Density @ 293 K: Unknown Color: Unknown More information about the naming of the heavy elements is available ...

Jan 24, 2020 · However, in 1979 the IUPAC recommended systematic placeholder names be given to unverified elements, so until the permanent name was decided, element 111 was called unununium (Uuu). Because of their discovery, the GSI team was allowed to suggest a new name.

roentgenium (Rg), artificially produced transuranium element of atomic number 111. In 1994 scientists at the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung [GSI]) in Darmstadt, Ger., formed atoms of element 111 when atoms of bismuth -209 were bombarded with atoms of nickel -62.

Sep 20, 2023 · The IUPAC called it unununium (Uuu), which is the placeholder name corresponding to the atomic number. Since basically no one could consistently spell or pronounce the IUPAC name, it went by the name “111” until the GSI proposed the name of roentgenium and element symbol Rg.

May 21, 2024 · Roentgenium is a metallic chemical element classified among the transactinides on the periodic table of elements. This element is one of the heaviest known to man, with an atomic number of 111; it was once known as unununium, a systematic name which is related to its atomic number.

Aug 21, 2018 · Nature Chemistry - Taye Demissie relates unununium’s unusually smooth route to roentgenium, and how predicting its properties relies on relativistic calculations.

Roentgenium was called unununium before it was formally discovered. Roentgenium was first observed in 1994 and several isotopes have been synthesized since its first discovery. The most stable known isotope is 281Rg with a half-life of ~20 seconds, which decays by spontaneous fission, like many other N=170 isotones.