Chemical Element: roentgenium

(Named for German physicist Wilhelm Conrad Roentgen)

Chemical-Element Information

Symbol: Rg
Atomic number: 111
Year discovered: 1994

Discovered by: S. Hofmann, V. Ninov, F. P. Hessberger, P. Armbruster, H. Folger, G. Münzenberg, H. J. Schott, A. G. Popeko, A. V. Yeremin, A. N. Andreyev, S. Saro, R. Janik, M. Lein, and others at GSI in Darmstadt, Germany.


  • Röntgen, or Roentgen, was born on March 27, 1845, in Lennkep, Prussia (now Remscheid, Germany) and died on February 10, 1923 in Munich, Germany.
  • Wilhelm Conrad Röntgen, as a German physicist, discovered X-rays on 8 November 1895, a new type of rays to which he gave this name in view of their uncertain nature.
  • Their use has subsequently revolutionized medicine, found wide application in technology, and heralded the age of modern physics, which is based on atomic and nuclear properties.
  • In 1901, six years after their discovery, the benefit of X-rays to mankind was so evident that Roentgen was awarded the first Nobel Prize in Physics.
  • His discovery of "x-rays" significantly contributed to modern physics and revolutionized diagnostic medicine.
  • Röntgen studied at the Polytechnic in ZŸrich and then was professor of physics at the universities of Strasbourg (1876-79), Giessen (1879-88), Würzburg (1888-1900), and Munich (1900-20).
  • His research also included work on elasticity, capillary action of fluids, specific heats of gases, conduction of heat in crystals, absorption of heat by gases, and piezoelectricity.
  • Röntgen determined that because the X-rays were not deflected by a magnet, they could not be a form of cathode rays.
  • He speculated that instead the X-rays might be longitudinal electromagnetic waves.
  • The possible medical use of X-rays was realized almost immediately.
  • Unlike other discoveries where the practical applications follow only after decades, physicians were using X-rays within months to inspect internal damage without surgery.
  • Today we know that X-rays are high energy, transverse electromagnetic waves similar to other forms of light.
  • Electromagnetic radiation ranges from high energy, short wave-length gamma and X-rays, through ultraviolet light, visible light, and infrared, to low energy, and long wave-length radio waves.
  • Despite the fact that Röntgen discovered nearly all the properties of X-rays within the first few weeks of investigation, the temporary name he used (X-rays) for the sake of brevity remains the name that is still generally used today (except in Germany where they usually refer to a "Röntgen" examination or report).
  • Element 111 was synthesized exactly 100 years after Roentgen's discovery.
  • To honor Wilhelm Conrad Roentgen, the name, roentgenium, was proposed for the element with atomic number 111.
  • The name roentgenium for the element of atomic number 111 (with symbol Rg) was officially approved as of November 1, 2004.

Name in other languages:

French: roentgenium

German: Roentgenium or Röntgenium

Italian: roentgenium

Spanish: roentgenium


You will find a special Röntgen biography,
if you want to know more about him.

Information about other elements may be seen at this Chemical Elements List.

A special unit about words that include chemo-, chem- may be seen here.


Related "roentgen, x-ray" units: roentgeno-; Roentgen Biography.