Presentation on theme: "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."— Presentation transcript:
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
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
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
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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