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 an alkali metal element denoted by the atomic symbol Cs. It has an atomic number of 55 and an atomic weight of 132.91. It is a very soft, white metal which is not particularly abundant in nature. It is typically found as a compound such as pollucite. In its pure form, it is the most reactive alkali metal. Cesium reacts violently with both liquid water and ice, and even moist air is often sufficient to ignite the metal. For safety, it must be transported and stored in kerosene, with which it does not react.
A very rare alkali metal, cesium was one of the first new elements discovered using the spectroscopic methods perfected by Robert Bunsen and Gustav Kirchhoff in 1860. These two German scientists had developed a method by which elements could be identified by examining the spectral lines produced when the element was heated or burned. After recording the spectra of all known elements, they soon discovered new spectral "fingerprints" belonging to previously unknown elements. One of these they named caesium from the Latin word for "sky blue" (after the blue color of its spectral lines).
Cesium is used mainly in photoelectric cells, but is also a component in radio tubes, military infrared lamps, and video equipment. In the 1940s, the American scientist Norman F. Ramsey, Jr. (1915-) designed an atomic clock whose phenomenal accuracy is based upon the precise frequencies within cesium atoms.