Types and Properties of Crystalline Solids

Now we can turn to the five most important types of solids, which are summarized in Table 12.5. Each is defined by the type(s) of particle(s) in the crystal, which determines the interparticle forces. You may want to review the bonding models (Chapter 9) to clarify how they relate to the properties of different solids. 

Ionic Solids In crystalline ionic solids, the unit cell contains particles with whole, rather than partial, charges. As a result, the interparticle forces (ionic bonds) are much stronger than the van der Waals forces in atomic or molecular solids. To maximize attractions, cations are surrounded by as many anions as possible, and vice versa, with the smaller of the two ions lying in the spaces (holes) formed by the packing of the larger. Because the unit cell is the smallest portion of the crystal that maintains the overall spatial arrangement, it is also the smallest portion that maintains the overall chemical composition. In other words, the unit cell has the same cation anion ratio as the empirical formula 

CHAPTER 12 Intermolecuhr Forces Liquids, Solids, and Phase Changes 

By far the most important network covalent solids are the silicates. They utilize a variety of bonding patterns, but nearly all consist of extended arrays of covalently bonded silicon and oxygen atoms. Quartz (Si02) is a common example. We ll discuss silicates, which form the structure of clays, rocks, and many minerals, when we consider the chemistry of silicon in Chapter 14. 

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The Solid State Structure, Properties, and Bonding 373 Structural Features of Solids 373 Types and Properties of Crystalline Solids 379... 

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