n. Symbol U
A dense silvery-white metallic element that is radioactive and toxic, is easily oxidized, and has numerous isotopes of which U-238 is the most abundant in nature. The element occurs in several minerals, including uraninite and carnotite, from which it is extracted and processed for use in research, nuclear fuels, and nuclear weapons. Atomic number 92; atomic weight 238.03; melting point 1,135°C; boiling point 4,131°C; specific gravity 19.1; valence 2, 3, 4, 5, 6. See Periodic Table.
[New Latin ūranium, named by German chemist Martin Heinrich Klaproth, who discovered the element in 1789, after New Latin Ūranus, the planet Uranus, discovered in 1781; see URANUS.]
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