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Published byLarry Warren Modified over 10 years ago
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Solids Ionic Crystals Strength of attractive forces in ionic crystals is indicated by Coulomb’s law, F = q 1 q 2 /r Forces tend to be very large Crystals are very rigid and brittle
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Solids Molecular Crystals Composed of either atoms of nonmetals or of covalent molecules Held together by London forces, dipole- dipole attractions, hydrogen bonding or a mixture of the 3 (weak forces). Tend to be soft crystals, with low MP
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Solids Network (Covalent) Crystals Has a lattice structure in which the atoms are covalently bonded to each other Result is one large molecule with a continuous network of covalent bonds. Ex. Diamond, silicon dioxide, silicon carbide, graphite In diamond- each C atom is covalently bonded to 4 other C atoms in a tetrahedral (sp 3 ) geometry. In graphite, each C atom is covalently bonded to 3 other C atoms in a trigonal planar (sp 2 ) geometry. The extra p e - that isn’t used in bonding holds the sheets weakly together, allowing them to slide. Silicon carbide
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Solids Amorphous (noncrystalline) solids Do not have a distinct, sharp MP. They soften gradually over a large temp. range Examples are glass and many plastics
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