All uranium chlorides react with water and air.
The use of uranium, in its natural oxide form, dates back to at least 79 C.E., when it was used to add a yellow color to ceramic glazes.
United States Federal government paid discovery bonuses and guaranteed purchase prices to anyone who found and delivered Uranium ore.
To be considered 'enriched' the uranium-235 fraction has to be increased to significantly greater than its concentration in naturally-occurring uranium.
Naturally occurring uranium is composed of three major isotopes, uranium-238 (99.28 percent natural abundance), uranium-235 (0.71 percent), and uranium-234 (0.0054 percent).
Both UC and UC2 are formed by adding carbon to molten uranium or by exposing the metal to carbon monoxide at high temperatures.
A few solid and semi-metallic compounds such as UO and US exist for the formal oxidation state uranium(II) but no simple ions are known to exist in solution for that state.
Uranium dioxide is the form in which uranium is most commonly used as a nuclear reactor fuel.
Two crystal modifications of uranium hydride exist: an ? form that is obtained at low temperatures and a ? form that is created when the formation temperature is above 250 °C.
From 1993 to 2005 the Material Protection, Control, and Accounting Program, operated by the federal government of the United States, spent approximately US$550 million to help safeguard uranium and plutonium stockpiles in Russia.
Antoine Becquerel discovered radioactivity by using uranium in 1896.
The UO2+ ion represents the uranium(V) state and is known to form compounds that include inorganic ions such as carbonate, chloride and sulfate, and various organic chelating agents.
Very pure uranium can be produced through the thermal decomposition of uranium halides on a hot filament.
Police in Asia, Europe, and South America on at least 16 occasions from 1993 to 2005 have intercepted shipments of smuggled bomb-grade uranium or plutonium, most of which was from ex-Soviet sources.
Uranium-233 is made from thorium-232 by neutron bombardment.
Under the right conditions of temperature and pressure, the reaction of solid UF4 with gaseous uranium hexafluoride (UF6) can form the intermediate fluorides of U2F9, U4F17, and UF5.
Uranium oxyhalides are water-soluble and include UO2F2, UOCl2, UO2Cl2, and UO2Br2.
Confirmation of this hypothesis came in 1939 and later work found that 2 1/2 neutrons are released by each fission of the rare uranium isotope uranium-235.
Ions that represent the four different oxidation states of uranium are soluble and therefore can be studied in aqueous solutions.
Uranium ore is mined in several ways: by open pit, underground or by leaching uranium from low-grade ores (see uranium mining).
The gas centrifuge process, where gaseous uranium hexafluoride (UF6) is separated by weight using high-speed centrifuges, has become the cheapest and leading enrichment process (lighter UF6 concentrates in the center of the centrifuge).
Uranium carbides and uranium nitrides are both relatively inert semimetallic compounds that are minimally soluble in acids, react with water, and can ignite in air to form U3O8.
The frenzy ended as suddenly as it had begun, when the U.S. governments stopped purchasing the uranium.
The decay series of uranium-235 (also called actinouranium) has 15 members that ends in lead-207, protactinium-231 and actinium-227.
The resulting UF6 white solid is highly reactive (by fluorination), easily sublimes (emitting a nearly perfect gas vapor), and is the most volatile compound of uranium known to exist.
The half-life of uranium-238 is about 4.5 billion years and that of uranium-235 is 700 million years, making them useful in dating the age of the Earth.
Hydrochloric and nitric acids dissolve uranium but nonoxidizing acids attack the element very slowly.
After entering the bloodstream, the absorbed uranium tends to bioaccumulate and stay for many years in bone tissue because of uranium's affinity for phosphates.
The major application of uranium in the military sector is in high-density penetrators.
Houses or structures which are over uranium deposits (either natural or man-made slag deposits) may have an increased incidence of exposure to radon gas.
Some micro-organisms, such as the lichen Trapelia involuta or the bacterium Citrobacter, can absorb concentrations of uranium that are up to 300 times higher than their environment.
Carbides of uranium include uranium monocarbide (UC), uranium dicarbide (UC2), and diuranium tricarbide (U2C3).
A majority of neutrons released by a fissioning atom of uranium-235 must impact other uranium-235 atoms to sustain the nuclear chain reaction needed for these applications.
A person can be exposed to uranium (or its radioactive daughters such as radon) by inhaling dust in air or by ingesting contaminated water and food.
The most common forms of uranium oxide are triuranium octaoxide (U3O8) and the aforementioned UO2.
Plants absorb some uranium from the soil they are rooted in.
Reduction of UF4 with hydrogen at 1000 °C produces uranium trifluoride (UF3).
Uranium (chemical symbol U, atomic number 92) is a silvery metallic chemical element in the actinide series of the periodic table.
Uranium metal reacts with nearly all nonmetallic elements and their compounds with reactivity increasing with temperature.
During the Cold War between the Soviet Union and the United States, huge stockpiles of uranium were amassed and tens of thousands of nuclear weapons were created, using enriched uranium and plutonium made from uranium.
Uranium in ores is extracted chemically and converted into uranium dioxide or other chemical forms usable in industry.
Finely-divided uranium metal presents a fire hazard because uranium is pyrophoric, so small grains will ignite spontaneously in air at room temperature.
Uranium decays slowly by emitting an alpha particle.
Two major types of fission bombs were built: a relatively simple device that uses uranium-235 and a more complicated mechanism that uses uranium-238-derived plutonium-239.
The largest single domestic source of uranium in the United states was the Colorado Plateau located in Colorado, Utah, New Mexico, and Arizona.
Fuel used for United States Navy submarine reactors is typically highly enriched in uranium-235 (the exact values are classified).
In 1841, Eugene-Melchior Peligot, who was Professor of Analytical Chemistry at the Central School of Arts and Manufactures in Paris, isolated the first sample of uranium metal by heating uranium tetrachloride with potassium.
The ore they exist in is 1.7 billion years old; at that time, uranium-235 comprised about three percent of the total uranium on Earth.
The Earth's crust from the surface to 25 km (15 miles) down is calculated to contain 1017 kg (2 x 1017 lb) of uranium while the oceans may contain 1013 kg (2 x 1013 lb).
Uranium-238 is an ? emitter, decaying through the 18-member uranium natural decay series into lead-206.
To be considered 'depleted', the uranium-235 isotope concentration has to have been decreased to significantly less than its natural concentration.
Bromides and iodides of uranium are formed by direct reaction of, respectively, bromine and iodine with uranium or by adding UH3 to those element's acids.
Uranium is an inner transition metal of the actinide series, situated in period 7 of the periodic table, between protactinium and neptunium.
The reduction of UCl4 by hydrogen produces uranium trichloride (UCl3) while the higher chlorides of uranium are prepared by reaction with additional chlorine.
Uranium is also the highest-numbered element to be found naturally in significant quantities on earth and is always found combined with other elements.
Uranium salts are mordants of silk or wool.
The isotope uranium-238 is also important because it absorbs neutrons to produce a radioactive isotope that subsequently decays to the isotope plutonium-239, which also is fissile.
Dry weight concentrations of uranium in food plants are typically lower with one to two micrograms per day ingested through the food people eat.
During the later stages of World War II, the entire Cold War and to a much lesser extent afterwards, uranium was used as the fissile explosive material to produce nuclear weapons.
Almost all the uranium is exported, but under strict International Atomic Energy Agency safeguards to satisfy the Australian people and government that none of the uranium is used in nuclear weapons.
The United States Government was the sole legal purchaser of the uranium.
Tank armor and the removable armor on combat vehicles are also hardened with depleted uranium (DU) plates.
One method of preparing uranium tetrachloride (UCl4) is to directly combine chlorine with either uranium metal or uranium hydride.
uranium nitrate as a toner), in lamp filaments, to improve the appearance of dentures, and in the leather and wood industries for stains and dyes.
Uranium metal can also be made through electrolysis of KUF5 or UF4, dissolved in a molten calcium chloride (CaCl2) and sodium chloride (NaCl).
Uranium metal has very high density, 65 percent more dense than lead, but slightly less dense than gold.
The process produces huge quantities of uranium that is depleted of uranium-235 and with a correspondingly increased fraction of uranium-238, called depleted uranium or 'DU'.
The greatest health risk from large intakes of uranium is toxic damage to the kidneys, because, in addition to being weakly radioactive, uranium is a toxic metal.
Yellow glass with 1 percent uranium oxide was found in a Roman villa on Cape Posilipo in the Bay of Naples, Italy by R. T. Gunther of the University of Oxford in 1912.
A team led by Enrico Fermi in 1934 observed that bombarding uranium with neutrons produces the emission of beta rays (electrons or positrons; see beta particle).
Commercial-grade uranium can be produced through the reduction of uranium halides with alkali or alkaline earth metals.
Uranium metal is used for X-ray targets in the making of high-energy X-rays.
Depleted uranium (uranium-238) is used in kinetic energy penetrators and armor plating.
Uranium metal heated to 250 to 300 °C reacts with hydrogen to form uranium hydride.
Australia has the world's largest uranium ore reserves—40 percent of the planet's known supply.
Enriched uranium typically has a uranium-235 concentration of between 3 and 5 percent.
The resulting mixture, called yellowcake, contains at least 75 percent uranium oxides.
Commercial nuclear power plants use fuel that is typically enriched to around 3% uranium-235, though some reactor designs (such as the CANDU reactors) can use unenriched uranium fuel.
Uranium was not seen as being particularly dangerous during much of the nineteenth century, leading to the development of various uses for the element.
The uranium-based Little Boy device became the first nuclear weapon used in war when it was detonated over the Japanese city of Hiroshima on August 6, 1945.
Uranium was also used in photographic chemicals (esp.
After one day, one gram of bacteria will encrust themselves with nine grams of uranyl phosphate crystals; creating the possibility that these organisms could be used to decontaminate uranium-polluted water.
Uranium was the first element that was found to be fissile.
Depleted uranium is also used as a shielding material in some containers used to store and transport radioactive materials.
Uranium nitrides obtained by direct exposure of the metal to nitrogen include uranium mononitride (UN), uranium dinitride (UN2), and diuranium trinitride (U2N3).
The heaviest naturally occurring element, uranium is nearly twice as dense as lead and weakly radioactive.
Uranium does not absorb through the skin, and alpha particles released by uranium cannot penetrate the skin.
Upon bombardment with slow neutrons, its uranium-235 isotope becomes a very short lived uranium-236 isomer which immediately divides into two smaller nuclei, releasing nuclear binding energy and more neutrons.
The experiments leading to the discovery of uranium's ability to fission (break apart) into lighter elements and release binding energy were conducted by Otto Hahn and Fritz Strassmann in Hahn's laboratory in Berlin.
Phase relationships in the uranium-oxygen system are highly complex.
Soon after, Fermi hypothesized that the fission of uranium might release enough neutrons to sustain a fission reaction.
The laser excitation method employs a laser beam of precise energy to sever the bond between uranium-235 and fluorine.
Triuranium octaoxide is (depending on conditions) the most stable compound of uranium and is the form most commonly found in nature.
All uranium fluorides are created using uranium tetrafluoride (UF4); UF4 itself is prepared by hydrofluorination or uranium dioxide.
Later, a much more complicated and far more powerful fusion bomb that uses a plutonium-based device in a uranium casing to cause a mixture of tritium and deuterium to undergo nuclear fusion was built.