uranium
/jʊˈreɪnɪəm
/noun [mass noun]
The chemical element of atomic number 92, a dense grey radioactive metal used as a fuel in nuclear reactors. (Symbol: U) It is not possible, however, to construct weapons directly out of uranium or slightly enriched uranium....
- All countries have uranium, uranium is a very common material around the world.
- It is not certain if the effects are due to the chemical or the radioactive properties of uranium.
Uranium is a chemically reactive metal belonging to the actinide series. Becquerel discovered radioactivity in uranium in 1896, and its capacity to undergo fission led to its use as a source of energy, though the fissile isotope, uranium-235, has to be separated from the more common uranium-238 before it can be used in nuclear weapons. The atom bomb exploded over Hiroshima in 1945 contained uranium-235.
Origin
Late 18th century: modern Latin, from Uranus: compare with tellurium.
A rare radioactive metal, uranium is found in the mineral pitchblende. The German chemist Martin Klaproth isolated the metal and called it uranium after the planet Uranus, which the astronomer Sir William Herschel had discovered less than a decade before, in 1781.