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Cambridge, University of

(Encyclopedia)Cambridge, University of, at Cambridge, England, one of the oldest English-language universities in the world. Originating in the early 12th cent. (legend places its origin even earlier than that of t...

bohrium

(Encyclopedia)bohrium bôrˈēəm [key], artificially produced radioactive chemical element; symbol Bh; at. no. 107; mass number of most stable isotope 270; m.p., b.p., sp. gr., and valence unknown. Situated in Gro...

nihonium

(Encyclopedia)nihonium nĭhōˈnēəm [key], artificially produced radioactive chemical element; symbol Nh; at. no. 113; mass number of most stable isotope 284; m.p., b.p., sp. gr., and valence unknown. Situated in...

poison

(Encyclopedia)poison, any agent that may produce chemically an injurious or deadly effect when introduced into the body in sufficient quantity. Some poisons can be deadly in minute quantities, others only if relati...

butter

(Encyclopedia)butter, dairy product obtained by churning the fat from milk until it solidifies. In most areas the milk of cows is the basis, but elsewhere that of goats, sheep, and mares has been used. Butter was k...

lithium

(Encyclopedia)lithium lĭthˈēəm [key] [Gr.,=stone], metallic chemical element; symbol Li; at. no. 3; interval in which at. wt. ranges 6.938–6.997; m.p. about 180.54℃; b.p. about 1,342℃; sp. gr. .534 at 20�...

magnetic resonance

(Encyclopedia)magnetic resonance, in physics and chemistry, phenomenon produced by simultaneously applying a steady magnetic field and electromagnetic radiation (usually radio waves) to a sample of atoms and then a...

rutherfordium

(Encyclopedia)rutherfordium rŭᵺˌərfôrˈdēəm [key], artificially produced radioactive chemical element; symbol Rf; at. no. 104; mass number of most stable isotope 265; m.p., b.p., and sp. gr. unknown; valenc...

activation energy

(Encyclopedia)CE5 Energy profile of an exothermic reaction: Although the total energy of the products is less than that of the reactants, the activation energy must be added to weaken or break existing bonds bef...

concentration

(Encyclopedia)concentration, in chemistry, measure of the relative proportions of two or more quantities in a mixture. The concentration of a solute is very important in studying chemical reactions because it deter...