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copernicium

(Encyclopedia)copernicium, artificially produced radioactive chemical element; symbol Cn; at. no. 112; mass number of most stable isotope 285; m.p., b.p., sp. gr., and valence unknown. Situated in Group 12 of the p...

combustion

(Encyclopedia)combustion, rapid chemical reaction of two or more substances with a characteristic liberation of heat and light; it is commonly called burning. The burning of a fuel (e.g., wood, coal, oil, or natura...

Barnard, Frederick Augustus Porter

(Encyclopedia)Barnard, Frederick Augustus Porter, 1809–89, American educator and mathematician, b. Sheffield, Mass., grad. Yale, 1828. After tutoring at Yale and teaching in institutions for the deaf and mute, he...

polarography

(Encyclopedia)polarography pōˌlərŏgˈrəfē [key], in chemistry, method for analyzing the composition of a dilute electrolytic solution (see electrolyte). Two electrodes are placed in the solution: One has a fi...

planetary science

(Encyclopedia)planetary science or planetology, study of planets and planetary systems as a whole. Planetary science applies the theories and methods of traditional disciplines such as astronomy, geology, physics, ...

Rush, Benjamin

(Encyclopedia)Rush, Benjamin, 1745?–1813, American physician, signer of the Declaration of Independence, b. Byberry (now part of Philadelphia), Pa., grad. College of New Jersey (now Princeton, 1760), M.D. Univ. o...

Sanger, Margaret Higgins

(Encyclopedia)Sanger, Margaret Higgins, 1879–1966, American leader in the birth control movement, b. Corning, N.Y. Personal experience and work as a public-health nurse, much of it on New York City's Lower East S...

rare-earth metals

(Encyclopedia)rare-earth metals, in chemistry, group of metals including those of the lanthanide series and actinide series and usually yttrium, sometimes scandium and thorium, and rarely zirconium. Promethium, whi...

niobium

(Encyclopedia)niobium nīōˈbēəm [key], metallic chemical element; symbol Nb; at. no. 41; at. wt. 92.90638; m.p. about 2,468℃; b.p. 4,742℃; sp. gr. 8.57 at 20℃; valence +2, +3, +4, or +5. Niobium is a rare...

Nobel, Alfred Bernhard

(Encyclopedia)Nobel, Alfred Bernhard älˈfrĕd bĕrnˈhärd nōbĕlˈ [key], 1833–96, Swedish chemist and inventor. Educated in St. Petersburg, Russia, he traveled as a youth and returned to St. Petersburg in 18...