roentgenium

Roentgenium is a synthetic chemical element with the symbol Rg and atomic number 111. It is a member of period 7 and group 11 and is categorized as a superheavy, highly radioactive metal that has not been observed in nature.

Roentgenium was first synthesized in 1994 by researchers at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, by bombarding a bismuth-209 target with nickel-64 ions. The discovery was reported by the GSI team, and the element was named roentgenium in 2004 after Wilhelm Conrad Röntgen, the discoverer of X-rays.

All roentgenium isotopes are radioactive and have very short half-lives, making detailed chemical studies impractical. The known isotopes have lifetimes measured in milliseconds to seconds, and no stable form has been observed.

Chemically, roentgenium is expected to behave as a heavy member of group 11, with properties influenced by relativistic effects. It is predicted to form oxidation states similar to copper, silver, and gold, but with deviations that challenge experimental confirmation.

Because of its short existence, roentgenium has no commercial applications. It is produced only in particle accelerators for basic research in nuclear physics and theoretical chemistry, helping to test models of superheavy-element behavior.