What is "uranium"

Uranium \U*ra"ni*um\, n. [NL., from Uranus the planet. See Uranus.] (Chem.) An element of the chromium group, found in certain rare minerals, as pitchblende, uranite, etc., and reduced as a heavy, hard, nickel-white metal which is quite permanent. Its yellow oxide is used to impart to glass a delicate greenish-yellow tint which is accompanied by a strong fluorescence, and its black oxide is used as a pigment in porcelain painting. Symbol U. Atomic weight 239.

Note: Uranium was discovered in the state of an oxide by Klaproth in 1789, and so named in honor of Herschel's discovery of the planet Uranus in 1781.

rare metallic element, 1797, named 1789 in Modern Latin by its discoverer, German chemist and mineralogist Martin Heinrich Klaproth (1743-1817), for the recently found planet Uranus (q.v.) + element ending -ium.

n. The element with atomic number 92 and symbol U.

n. a heavy toxic silvery-white radioactive metallic element; occurs in many isotopes; used for nuclear fuels and nuclear weapons [syn: U, atomic number 92]

Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-white metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weakly radioactive because all its isotopes are unstable (with half-lives of the six naturally known isotopes, uranium-233 to uranium-238, varying between 69 years and 4.5 billion years). The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99%) and uranium-235 (which has 143 neutrons). Uranium has the second highest atomic weight of the primordially occurring elements, lighter only than plutonium. Its density is about 70% higher than that of lead, and slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite.

In nature, uranium is found as uranium-238 (99.2739–99.2752%), uranium-235 (0.7198–0.7202%), and a very small amount of uranium-234 (0.0050–0.0059%). Uranium decays slowly by emitting an alpha particle. The half-life of uranium-238 is about 4.47 billion years and that of uranium-235 is 704 million years, making them useful in dating the age of the Earth.

Many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 has the distinction of being the only naturally occurring fissile isotope. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor. Another fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. Uranium-238 has a small probability for spontaneous fission or even induced fission with fast neutrons; uranium-235 and to a lesser degree uranium-233 have a much higher fission cross-section for slow neutrons. In sufficient concentration, these isotopes maintain a sustained nuclear chain reaction. This generates the heat in nuclear power reactors, and produces the fissile material for nuclear weapons. Depleted uranium (U) is used in kinetic energy penetrators and armor plating. Uranium is used as a colorant in uranium glass, producing lemon yellow to green colors. Uranium glass fluoresces green in ultraviolet light. It was also used for tinting and shading in early photography.

The 1789 discovery of uranium in the mineral pitchblende is credited to Martin Heinrich Klaproth, who named the new element after the planet Uranus. Eugène-Melchior Péligot was the first person to isolate the metal and its radioactive properties were discovered in 1896 by Henri Becquerel. Research by Otto Hahn, Lise Meitner, Enrico Fermi and others, such as J. Robert Oppenheimer starting in 1934 led to its use as a fuel in the nuclear power industry and in Little Boy, the first nuclear weapon used in war. An ensuing arms race during the Cold War between the United States and the Soviet Union produced tens of thousands of nuclear weapons that used uranium metal and uranium-derived plutonium-239. The security of those weapons and their fissile material following the breakup of the Soviet Union in 1991 is an ongoing concern for public health and safety. See Nuclear proliferation.

Uranium may refer to:

Uranium was an American television program about heavy metal which aired on Fuse TV (MMUSA when the program debuted) in the early 2000s (decade). After establishing herself as the host of MMUSA's Tastemakers program, Juliya Chernetsky, along with network producers, created Uranium as an outlet for the broad range of heavy metal subgenres. Debuting in 2002 and hosted by a 19-year-old Chernetsky, it served as Fuse TV's equivalent to MTV's Headbangers Ball, a long-canceled series that was revived shortly after Uranium's debut. With new episodes premiering Friday nights at 9pm ET, the program traditionally ran a half-hour featuring an interview with a band and music videos.

Uranium ended in 2006 due to Juliya's departure from Fuse TV, but reruns still occasionally air late at night. Current airings often consist entirely of video blocks without interview segments. Over the years, Fuse TV has introduced various new programs in place of Uranium, and Chernetsky has continued her career in heavy metal journalism.