roentgenium
/rɛntˈɡɛniəm/
noun
- A highly radioactive chemical element with the symbol Rg and atomic number 111. It is a synthetic metal that does not occur naturally and is produced in laboratories.
- Because roentgenium is so unstable, it decays into other elements within seconds.
- Researchers study roentgenium to learn more about the properties of superheavy elements.
- Roentgenium was first created in 1994 by scientists in Germany.