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tabun

(Encyclopedia)tabun täˈbən [key], liquid chemical compound used as a nerve gas. It boils at 240℃ with some decomposition. The liquid is colorless to brownish; its vapors have a fruity odor similar to that of b...

glycol

(Encyclopedia)glycol glīˈkōl [key], dihydric alcohol in which the two hydroxyl groups are bonded to different carbon atoms; the general formula for a glycol is (CH2)n(OH)2. The most important glycol is the simpl...

scandium

(Encyclopedia)scandium skănˈdēəm [key], metallic chemical element; symbol Sc; at. no. 21; at. wt. 44.95591; m.p. 1,541℃; b.p. 2,831℃; sp. gr. 2.99 at 20℃; valence +3. Scandium is a soft silver-white metal...

magnesium

(Encyclopedia)magnesium măgnēˈzēəm, –zhəm [key], metallic chemical element; symbol Mg; at. no. 12; at. wt. 24.3050; m.p. about 648.8℃; b.p. about 1,090℃; sp. gr. 1.738 at 20℃; valence +2. In 1808, Sir...

petrochemical

(Encyclopedia)petrochemical, any one of a large group of chemicals derived from a component of petroleum or natural gas. The cracking processes for manufacturing gasoline produce vast quantities of gaseous hydrocar...

calcination

(Encyclopedia)calcination kălˌsənāˈshən [key], in metallurgy, process of heating solid material to drive off volatile chemically combined components, e.g., carbon dioxide. It is sometimes a step in the extrac...

cassiterite

(Encyclopedia)cassiterite kəsĭtˈərīt [key], heavy, brown-to-black mineral, tin oxide, SnO2, crystallizing in the tetragonal system. It is found as short prismatic crystals and as irregular masses, usually in v...

zinc

(Encyclopedia)zinc, metallic chemical element; symbol Zn; at. no. 30; at. wt. 65.38; m.p. 419.58℃; b.p. 907℃; sp. gr. 7.133 at 25℃; valence +2. Zinc is a lustrous bluish-white metal. It is found in Group 12 o...

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 +...