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valence, in chemistry

(Encyclopedia)valence, combining capacity of an atom expressed as the number of single bonds the atom can form or the number of electrons an element gives up or accepts when reacting to form a compound. Atoms are c...

battery, electric

(Encyclopedia)CE5 Lead storage cell: At the lead-dioxide electrode, electrons from the circuit combine with lead dioxide and sulfuric acid to form lead sulfate and water. At the spongy-lead electrode, lead react...

molybdenum

(Encyclopedia)molybdenum məlĭbˈdənəm [key] [Gr.,=leadlike], metallic chemical element; symbol Mo; at. no. 42; at. wt. 95.96; m.p. about 2,617℃; b.p. about 4,612℃; sp. gr. 10.22 at 20℃; valence +2, +3, +4...

plutonium

(Encyclopedia)plutonium plo͞otōˈnēəm [key], radioactive chemical element; symbol Pu; at. no. 94; mass no. of most stable isotope 244; m.p. 641℃; b.p. 3,232℃; sp. gr. 19.84 at 20℃; valence +3, +4, +5, or ...

enzyme

(Encyclopedia)enzyme, biological catalyst. The term enzyme comes from zymosis, the Greek word for fermentation, a process accomplished by yeast cells and long known to the brewing industry, which occupied the atten...

critical mass

(Encyclopedia)critical mass: see chain reaction. ...

Tsiolkovsky, Konstantin Eduardovich

(Encyclopedia)Tsiolkovsky, Konstantin Eduardovich kənstəntyēnˈ ĕdwärˈdəvĭchˈ tsēōlkŏvˈskē [key], 1857–1935, Russian inventor and rocket expert. He lost his hearing in childhood, and, as he could no...

Wassermann, August von

(Encyclopedia)Wassermann, August von wŏsˈərmən, Ger. ouˈgo͝ost fən väsˈərmän [key], 1866–1925, German physician and bacteriologist. In Berlin he was director of the department of experimental therapy a...

Wurtz, Charles Adolphe

(Encyclopedia)Wurtz, Charles Adolphe shärl ädôlfˈ vürts [key], 1817–84, French chemist. He was professor at the Sorbonne (1852–75), at the Faculty of Medicine, Paris (1853–75), and at the Faculty of Scie...

cold fusion

(Encyclopedia)cold fusion or low-temperature fusion, nuclear fusion of deuterium, an isotope of hydrogen, at or relatively near room temperature. Fusion, the reaction involved in the release of the destructive ener...