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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The octet rule is used to describe the attraction of elements towards having, whenever possible, eight valence-shell electrons (4 electron pairs) in their outer shell. Because a full outer shell with eight electrons is relatively stable, many atoms lose or gain electrons to obtain an electron configuration like that of the nearest noble gas. Except for Helium (with a filled 1s shell), noble gases have eight electrons in their valence shells. The octet rule is used when drawing Lewis dot structures.
The components of table salt, sodium and chloride ions, illustrate the octet rule. Sodium (Na) with an electron configuration of 1s22s22p63s1 sheds its outermost 3s electron and, as a result, the Na+ ion has an electron configuration of 1s22s22p6. This is the same electron configuration as neon, a noble gas (i.e., highly stable and relatively nonreactive).
Chlorine (Cl), on the other hand, has an electron configuration of 1s22s22p63s23p5. Chlorine needs one electron to fill its outermost third shell with eight electrons. When chlorine takes on the electron shed by sodium then the Cl+ ion's electron configuration becomes 1s22s22p63s23p6. This is the same configuration as Argon, another noble gas.
The octet rule, however, does not accurately predict the electron configurations of all molecules and compounds. Not every nonmetal, nor metal, can form compounds that satisfies the octet rule. As a result, the octet rule must be used with caution when predicting the electron configurations of molecules and compounds. Some atoms violate the octet rule and surround themselves with more than four electron pairs.
In general, the octet rule works for representative metals (Groups IA, IIA) and nonmetals, but not for the transition, inner-transition or post-transition elements. These elements seek additional stability by having filled half-filled or filled orbitals d or f subshell orbitals.