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cesium
(Encyclopedia)cesium sēˈzēəm [key] [Lat.,=bluish gray], a metallic chemical element; symbol Cs; at. no. 55; at. wt. 132.90545; m.p. 28.4℃; b.p. 669.3℃; sp. gr. 1.873 at 20℃; valence +1. Cesium is a ductil...Cs, chemical symbol
(Encyclopedia)Cs, symbol for the element cesium. ...Periodic Table of the Elements: Cesium
(Encyclopedia)Periodic Table of the Elements: Cesium ...alkali metals
(Encyclopedia)alkali metals, metals found in Group 1 of the periodic table. Compared to other metals they are soft and have low melting points and densities. Alkali metals are powerful reducing agents and form univ...atomic clock
(Encyclopedia)atomic clock, electric or electronic timekeeping device that is controlled by atomic or molecular oscillations. A timekeeping device must contain or be connected to some apparatus that oscillates at a...Kirchhoff, Gustav Robert
(Encyclopedia)Kirchhoff, Gustav Robert go͝osˈtäf rōˈbĕrt kĭrkhˈhôf [key], 1824–87, German physicist. He served as professor of physics at the universities of Breslau (1850–54), Heidelberg (1854–74), ...flame test
(Encyclopedia)flame test, test used in the identification of certain metals. It is based on the observation that light emitted by any element gives a unique spectrum when passed through a spectroscope. When a salt ...francium
(Encyclopedia)francium frănˈsēəm [key] [from France], radioactive chemical element; symbol Fr; at. no. 87; mass no. of most stable isotope 223; m.p. about 27℃ (estimated); b.p. 677℃ (estimated); sp. gr. unk...second
(Encyclopedia)second, abbr. sec or s, fundamental unit of time in all systems of measurement. In practical terms, the second is 1/60 of a minute, 1/3,600 of an hour, or 1/86,400 of a day. Since the length of the da...Bunsen, Robert Wilhelm
(Encyclopedia)Bunsen, Robert Wilhelm bŭnˈsən, Ger. rōˈbĕrt vĭlˈhĕlm bo͝onˈzən [key], 1811–99, German scientist, educated at the Univ. of Göttingen, where he received his doctorate in 1830. He served ...Browse by Subject
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