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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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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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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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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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thorium
thorium [from Thor ], radioactive chemical element; symbol Th; at. no. 90; at. wt. 232.0381; m.p. about 1,750°C; b.p. about 4,790°C; sp. gr. 11.7 at 20°C; valence +4.
Thorium is a soft, ductile, lustrous, silver-white, radioactive metal. At ordinary temperatures it has a face-cent...
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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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radioactivity
radioactivity spontaneous disintegration or decay of the nucleus of an atom by emission of particles, usually accompanied by electromagnetic radiation . The energy produced by radioactivity has important military and industrial applications. However, the rays emitted by radioactive substances ca...
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nuclear energy
nuclear energy the energy stored in the nucleus of an atom and released through fission, fusion, or radioactivity . In these processes a small amount of mass is converted to energy according to the relationship E = mc2 , where E is energy, m is mass, and c is the speed of light (see ...
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nuclear reactor
nuclear reactor device for producing controlled release of nuclear energy . Reactors can be used for research or for power production. A research reactor is designed to produce various beams of radiation for experimental application; the heat produced is a waste product and is dissipated as effici...
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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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