All practice pages/Interatomic theory/Elements
Element 92, an actinide
The heaviest element found in nature in quantity, the fuel of nuclear power, and the element in which radioactivity was discovered.
Period 7, in the actinide row set below the main table. The other actinides are tinted, and every cell opens its own article.
Radioactive, like every actinide. It gives up electrons to form positive ions.
More common in the crust than silver or tin. It is mined as uraninite, also called pitchblende, and other ores, mostly in Kazakhstan, Canada, Namibia and Australia. About 2 billion years ago, uranium ore at Oklo in Gabon ran as a natural nuclear reactor.
Martin Heinrich Klaproth found it in pitchblende in 1789 and named it after the planet Uranus, discovered eight years earlier. Eugène-Melchior Péligot isolated the metal in 1841, and in 1896 Henri Becquerel discovered radioactivity when uranium salts fogged a wrapped photographic plate.
Nuclear power plants run on uranium enriched to a few percent uranium-235 and supply about a tenth of the world's electricity; uranium also fuels naval reactors and nuclear weapons. Depleted uranium, left over from enrichment, is dense enough for armor-piercing ammunition, tank armor and aircraft counterweights. Uranium glass, which glows green under ultraviolet light, was popular in the early 1900s.
Only weakly radioactive, but chemically toxic to the kidneys. Enriched uranium and the products of its fission are far more dangerous.