(L. rubidus, deepest red) Discovered in 1861 by Bunsen and Kirchoff. It is the 16th most abundant element in the earth's crust. Minerals recovered from California, Michigan and Mantinoba. Naturally occuring rubidium contains two isotopes, Rb-85 and Rb-87. It is radioactive enough to expose a photographic film in 30 to 60 days.
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soft, silvery-white, alkali metal, ignites in air, in water it reacts violently (burns the hydrogen gas forming), stored in mineral oil or dry vacuum container, forms four oxides (hence the four oxidation #'s), relatively rare
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used as a radioactive tracer, photocell component, making special glasses