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Unformatted text preview: Materials Science Fall, 2007 Page 22 A familiar example of an ionic solid is table salt, NaCl. Sodium has a single elec- tron in its outer shell. Chlorine has seven electrons in its valence shell. The transfer of an electron from Na to Cl creates the ions Na + and Cl- , both of which have inert-gas elec- tron configurations. In the solid state the Na + and Cl- ions minimize their energies by surrounding themselves with ions of the opposite type, as illustrated in Fig. 2.5. It is not particularly helpful to picture a NaCl molecule in the solid state; since the ions are not paired there is no unambiguous way to decide which particular ions belong to a given molecule. It is more useful to picture the solid as a stoichiometric mixture of Na + and Cl- ions. = Na + = Cl- Fig. 2.5: Schematic illustration of bonding in NaCl. Most metal oxides and halides have predominantly ionic bonding. Because the valence electrons are localized and tightly bound to individual ions, an ionically bonded...
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This note was uploaded on 01/26/2010 for the course ENGLISH 45 taught by Professor Morris during the Spring '10 term at Berkeley.
- Spring '10