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meitnerium

(Encyclopedia)meitnerium mītnĭrˈēəm [key], artificially produced radioactive chemical element; symbol Mt; at. no. 109; mass number of most stable isotope 276; m.p., b.p., sp. gr., and valence unknown. Situated...

erbium

(Encyclopedia)erbium ûrˈbēəm [key] [from Ytterby, a town in Sweden], metallic chemical element; symbol Er; at. no. 68; at. wt. 167.259; m.p. 1,529℃; b.p. 2,863℃; sp. gr. 9.05 at 25℃; valence +3. Erbium is...

osmium

(Encyclopedia)osmium ŏzˈmēəm [key], metallic chemical element; symbol Os; at. no. 76; at. wt. 190.23; m.p. 3,045±30℃; b.p. 5,027±100℃; sp. gr. 22.57 at 20℃; valence usually +0 to +8. Osmium is a very ha...

uranium

(Encyclopedia)uranium yo͞orāˈnēəm [key], radioactive metallic chemical element; symbol U; at. no. 92; mass number of most stable isotope 238; m.p. 1,132℃; b.p. 3,818℃; sp. gr. 19.1 at 25℃; valence +3, +4...

Levi, Primo

(Encyclopedia)Levi, Primo prēˈmō lāˈvē [key], 1919–87, Italian writer. A chemist of Jewish descent, Levi was sent to the concentration camp at Auschwitz during World War II. His first memoir, If This Is a M...

Kolwezi

(Encyclopedia)Kolwezi kōlwĕzˈē [key], city (1984 pop. 416,122), Haut-Katanga prov., SE Congo (Kinshasa). It is a center for copper and cobalt mining. There are copper-ore concentration plants, a zinc refinery, ...

mineral

(Encyclopedia)mineral, inorganic substance occurring in nature, having a characteristic and homogeneous chemical composition, definite physical properties, and, usually, a definite crystalline form. A few of the mi...

curium

(Encyclopedia)curium kyo͝orˈēəm [key], artificially produced radioactive chemical element; symbol Cm; at. no. 96; mass no. of most stable isotope 247; m.p. about 1,340℃; b.p. 3,110℃; sp. gr. 13.5 (calculate...

oganesson

(Encyclopedia)oganesson ōˈgənĕsˌən [key], artificially produced radioactive chemical element; symbol Og; at. no. 118; mass number of most stable isotope 294; m.p., b.p., sp. gr., and valence unknown. Situated...

dysprosium

(Encyclopedia)dysprosium dĭsprōˈzēəm [key] [Gr.,=hard to get at], metallic chemical element; symbol Dy; at. no. 66; at. wt. 162.500; m.p. 1,412℃; b.p. 2,562℃; sp. gr. 8.54 at 25℃; valence+3. Dysprosium i...