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actinium

(Encyclopedia)actinium ăktĭnˈēəm [key] [Gr.,=like a ray], radioactive chemical element; symbol Ac; at. no. 89; mass number of most stable isotope 227; m.p. about 1,050℃; b.p. 3,200℃±300℃; sp. gr. 10.07;...

Saint-Denis, city, France

(Encyclopedia)Saint-Denis săN-dənēˈ [key], city (1990 pop. 90,806), Seine–Saint-Denis dept., N central France. It is an industrial suburb N of Paris. Metals, chemicals, machinery, electronics, and food produc...

Sherman, John

(Encyclopedia)Sherman, John, 1823–1900, American statesman, b. Lancaster, Ohio; brother of William Tecumseh Sherman. He studied law, was admitted (1844) to the bar, and practiced law several years in Mansfield, O...

selenium

(Encyclopedia)selenium səlēˈnēəm [key], nonmetallic chemical element; symbol Se; at. no. 34; at. wt. 78.96; m.p. 217℃; b.p. about 685℃; sp. gr. 4.81 at 20℃; valence −2, +4, or +6. Selenium is directly ...

rhenium

(Encyclopedia)rhenium rēˈnēəm [key], metallic chemical element; symbol Re; at. no. 75; at. wt. 186.207; m.p. about 3,180℃; b.p. about 5,625℃; sp. gr. 21.02 at 20℃; valence −1, +2, +3, +4, +5, +6, or +7....

protactinium

(Encyclopedia)protactinium prōˌtăktĭnˈēəm [key], radioactive chemical element; symbol Pa; at. no. 91; mass number of most stable isotope 231; m.p. greater than 1,600℃; b.p. 4,026℃; sp. gr. 15.37 (calcula...

Yukon, territory, Canada

(Encyclopedia)CE5 Yukon, territory (2001 pop. 28,674), 207,076 sq mi (536,327 sq km), NW Canada. The territory's history began with the explorations in the 1840s of Robert Campbell and John Bell, fur traders f...

De Soto, Hernando

(Encyclopedia)De Soto, Hernando dĭsōˈtō, Span. ĕrnänˈdō dā sōˈtō [key], c.1500–1542, Spanish explorer. After serving under Pedro Arias de Ávila in Central America and under Francisco Pizarro in Peru,...

germanium

(Encyclopedia)germanium jərmāˈnēəm [key] [from Germany], semimetallic chemical element; symbol Ge; at. no. 32; at. wt. 72.63; m.p. 937.4℃; b.p. 2,830℃; sp. gr. 5.323 at 25℃; valence +2 or +4. Pure german...

lanthanum

(Encyclopedia)lanthanum lănˈthənəm [key] [Gr.,=to lie hidden], metallic chemical element; symbol La; at. no. 57; at. wt. 138.90547; m.p. about 920℃; b.p. about 3,460℃; sp. gr. 6.19 at 25℃; valence +3. Lan...