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thorium

(Encyclopedia)thorium thôrˈēəm [key] [from Thor], radioactive chemical element; symbol Th; at. no. 90; mass number of most stable isotope 232; m.p. about 1,750℃; b.p. about 4,790℃; sp. gr. 11.7 at 20℃; va...

carbon

(Encyclopedia)CE5 The three solid forms of pure carbon: In the diamond crystal each carbon atom is surrounded symmetrically by four other carbons (at each of the four corners of a tetrahedron). In the graphite c...

Latrobe, Benjamin Henry

(Encyclopedia)Latrobe, Benjamin Henry (Benjamin Henry Boneval Latrobe) lətrōbˈ [key], 1764–1820, American architect, b. Yorkshire, England. He is considered the first professional architect in the United State...

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...

Koizumi, Junichiro

(Encyclopedia)Koizumi, Junichiro jo͝onēˈchērō kōēˈzo͞omē [key], 1942–, Japanese political leader, b. Yokosuka. From a political family, he studied economics at Keio Univ. (grad. 1967). He entered politi...

Free-Soil party

(Encyclopedia)Free-Soil party, in U.S. history, political party that came into existence in 1847–48 chiefly because of rising opposition to the extension of slavery into any of the territories newly acquired from...

gadolinium

(Encyclopedia)gadolinium gădəlĭnˈēəm [key], metallic chemical element; symbol Gd; at. no. 64; at. wt. 157.25; m.p. 1,312℃; b.p. 3,233℃; sp. gr. 7.898 at 25℃; valence +3. Gadolinium is a malleable, ducti...

equivalent weight

(Encyclopedia)equivalent weight. The equivalent weight of an element or radical is equal to its atomic weight or formula weight divided by the valence it assumes in compounds. The unit of equivalent weight is the a...

praseodymium

(Encyclopedia)praseodymium prāˌzēōdĭmˈēəm, –sēō– [key] [Gr., =green twin], metallic chemical element; symbol Pr; at. no. 59; at. wt. 140.90765; m.p. 931℃; b.p. 3,512℃; sp. gr. about 6.8; valence +...

ruthenium

(Encyclopedia)ruthenium ro͞othēˈnēəm [key], metallic chemical element; symbol Ru; at. no. 44; at. wt. 101.07; m.p. about 2,310℃; b.p. about 3,900℃; sp. gr. 12.41 at 20℃; valence commonly +2, +3, +4, +6, ...