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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Certain molecules differ from one another only in the fact that one is the mirror image of the other. These molecules are known as enantiomers (from the Greek word for "opposite"). Although enantiomeric pairs have identical physical and chemical properties, the fact that the two molecules are mirror images of each other causes them to exhibit different optical behavior.
An ordinary light beam consists of a group of electromagnetic waves that vibrate in all directions. When a beam of such light passes through a polarizer, only those waves vibrating in a specific plane are transmitted. Almost all molecules are theoretically capable of producing a slight rotation of the plane of plane-polarized light, with the magnitude and direction of the rotation in part dependent on the molecule's orientation when it is struck by the beam. In an optically inactive solution, the beam is as likely to encounter a molecule in its mirror-image orientation as in its original orientation, with the result that all the rotations produced by individual molecules cancel out.
If a polarized beam is passed through a solution consisting of only one enantiomeric type, however, the beam does not encounter any of the molecule's mirror images and so emerges with its plane of polarization rotated. Separate enantiomers rotate the plane of polarized light by the same amount, but in opposite directions. Because these molecules show different behaviors under plane polarized light, they are said to be optically active.