Roentgenium

Chemical element with atomic number 111 (Rg)

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. The most stable known isotope, roentgenium-282, has a half-life of 130 seconds, although the unconfirmed roentgenium-286 may have a longer half-life of about 10.7 minutes.

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