The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
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Cesium is the fifth member of the alkali family, the elements that make up Group 1 of the periodic table. Its atomic number is 55, its atomic mass is 132.9054, and its chemical symbol is Cs.
Cesium is a silvery white, shiny metal that is very soft and ductile. Its melting point is so low (83.3°F or 28.5°C) that it melts easily in the heat of a person's hand. Its boiling point is 1,301°F (705°C) and its density is 1.90 grams per cubic centimeter.
Cesium is a very active metal, one of the most active of all elements. It reacts violent with oxygen in the air and with water. So much energy is released in the latter reaction that the hydrogen formed as a product ignites. Cesium is normally stored under kerosene as a safety precaution to prevent it from reacting with oxygen or water vapor in the air. Cesium also reacts vigorously with acids, the halogens, sulfur, and phosphorus.
Cesium is moderately abundant in the Earth's crust with an estimated abundance of about 1-3 parts per million. It is found in an ore of lithium called lepidolite but, most abundantly, in the ore known as pollucite (Cs4Al4Si9O26).
Cesium was discovered in 1861 by two German chemists, Robert Bunsen and Gustav Kirchoff. The two had been instrumental in developing the new analytical technique of spectroscopy, and they found spectral lines for a previously unidentified element while studying a sample of spring water. They suggested the name cesium, from the Latin word caesius meaning "sky blue" because blue is the color of the element's spectral lines.
Cesium and its compounds have relatively few commercial uses. It is used in photovoltaic cells that convert the energy of sunlight into electricity. It is also used in the cesium clock, a device that measures time by means of the wavelength of light given off by one of the elements isotopes, cesium- 133.