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plutonium
plutonium , radioactive chemical element; symbol Pu; at. no. 94; mass no. of most stable isotope 244; m.p. 641°C; b.p. 3,232°C; sp. gr. 19.84 at 20°C; valence +3, +4, +5, or +6. Plutonium is a silver-gray radioactive metal that has six allotropic forms (see allotropy ). It is a member o...
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uranium
uranium , radioactive metallic chemical element; symbol U; at. no. 92; at. wt. 238.0289; m.p. 1,132°C; b.p. 3,818°C; sp. gr. 19.1 at 25°C; valence +3, +4, +5, or +6.
Properties
Uranium is a hard, dense, malleable, ductile, silver-white, radioactive metal of the actinide series...
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pitchblende
pitchblende , dark, lustrous, heavy mineral, a source of radium and uranium. Largely natural uranium oxides, triuranium octaoxide (U 3 O 8 ) and uranium dioxide (UO 2 ), it usually contains some lead and variable amounts of thorium and rare-earth elements. It is massive in form, frequently with a bo...
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actinium series
actinium series natural radioactive decay series beginning with uranium -235 (also called actinouranium) and ending with lead -207. See radioactivity .
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Port Hope
Port Hope town (1991 pop. 11,505), SE Ont., Canada, on Lake Ontario, E of Toronto. It has a large plant for refining uranium ore and is a summer resort.
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Manhattan Project
Manhattan Project the wartime effort to design and build the first nuclear weapons ( atomic bombs ). With the discovery of fission in 1939, it became clear to scientists that certain radioactive materials could be used to make a bomb of unprecented power. U.S. President Franklin Delano Roosevelt re...
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Martin Heinrich Klaproth
Martin Heinrich Klaproth , 1743-1817, German chemist. He is often referred to as the father of analytic chemistry. He recognized (1789) the presence of zirconium in the ore zirconia and of uranium in a precipitate of pitchblende. He also worked on other elements, including titanium and tellurium.
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Krugersdorp
Krugersdorp , city (1991 pop. 196,213), Gauteng, NE South Africa. The chief industrial city of the W Witwatersrand , Krugersdorp is the center for a region where gold, manganese, asbestos, lime, and uranium are mined. The city has uranium extraction plants. It also serves as the trade center for th...
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actinide series
actinide series a series of radioactive metallic elements in Group 3 of the periodic table . Members of the series are often called actinides, although actinium (at. no. 89) is not always considered a member of the series. The series always includes the 14 elements with atomic numbers 90 through...
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centrifuge
centrifuge , device using centrifugal force to separate two or more substances of different density, e.g., two liquids or a liquid and a solid. The centrifuge consists of a fixed base or frame and a rotating part in which the mixture is placed and then spun at high speed. One type is used for the se...
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