Roentgenium

Roentgenium is a synthetic, highly radioactive transition metal, but its chemistry has not yet been experimentally confirmed. It does not occur naturally in deposits and has no practical uses. Scientists create it a few atoms at a time in particle accelerators by firing nickel nuclei at a bismuth target; the two nuclei can fuse to form roentgenium. Its atoms decay quickly, so researchers identify them from their decay products rather than collecting a visible sample. Roentgenium is named for Wilhelm Röntgen, the physicist who discovered X-rays. Some properties, such as its likely metallic character, are predictions based on its place among the transition metals—not direct observations.