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rhodium
(Encyclopedia)rhodium rōˈdēəm [key], metallic chemical element; symbol Rh; at. no. 45; at. wt. 102.90550; m.p. about 1,966℃; b.p. 3,727±100℃; sp. gr. 12.41 at 20℃; valence +2, +3, +4, +5, or +6. Rhodium ...Witwatersrand
(Encyclopedia)Witwatersrand wĭtwôˈtərzrăndˌ [key] [Afrik.,=white water ridge] or the Rand, region, Gauteng prov. (formerly a part of Transvaal), South Africa. The area, which forms the watershed between the V...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....metric system
(Encyclopedia)CE5 metric system, system of weights and measures planned in France and adopted there in 1799; it has since been adopted by most of the technologically developed countries of the world. It is based...mass extinction
(Encyclopedia)mass extinction, the extinction of a large percentage of the earth's species, opening ecological niches for other species to fill. There have been at least ten such events. The five greatest were thos...metal
(Encyclopedia)metal, chemical element displaying certain properties by which it is normally distinguished from a nonmetal, notably its metallic luster, the capacity to lose electrons and form a positive ion, and th...Cretaceous period
(Encyclopedia)Cretaceous period krĭtāˈshəs [key], third and last period of the Mesozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table), lasting from approximately 144 to 65 millio...Elements (table)
(Encyclopedia)Elements 1 Parentheses indicate most stable isotope; brackets enclose lower and upper bounds of weight variation. ...Browse by Subject
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