23,24 - Chem 11500 Lectures 23-24 Reading: 12.6 1 This Week...

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1 Chem 11500 Lectures 23-24 Reading: 12.6
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2 This Week in Chemistry Attend lecture today! Lab and recitation are not held this week. No classes Wed-Friday for Thanksgiving holiday.
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3 Crystalline solids When most liquids are cooled, they eventually freeze and form crystalline solids , solids in which the atoms, ions, or molecules are arranged in a definite repeating pattern .
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4 Crystalline solids Some solids (such as diamonds and the individual grains in sugar and table salt) are single crystal. Most common crystalline solids are aggregates of many small crystals. Common examples of the latter are sandstone, chunks of ice, granite, and metal objects. Granite tile for countertops.
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5 Amorphous solids Tar, molten glass, molten plastics, and molten butter, consist of large molecules or a mixture of molecules that cannot move readily. As the temperature is lowered, their molecules move more and more slowly and finally stop in random positions. The resulting materials are called amorphous solids or glasses. Such solids lack an ordered internal structure . Common examples include candle wax, butter, glass, and plastics.
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6 Major Types of Crystalline Solids - Information from Table 12.5 Interparticle Forces Physical Behavior Atomic (Noble gases) Molecular Ionic Metallic Network Soft, very low mp, poor thermal & electrical conductors Dispersion Dispersion, dipole-dipole, H bonds Fairly soft, low to moderate mp, poor thermal & electrical conductors Covalent bond Metallic bond Ion-ion attraction Very hard, very high mp, usually poor thermal and electrical conductors Soft to hard, low to very high mp, excellent thermal and electrical conductors, malleable and ductile Hard & brittle, high mp, good thermal & electrical conductors when molten Type
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7 Unit cells One of the characteristic properties of a crystalline solid is
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This note was uploaded on 02/17/2012 for the course CHM 115 taught by Professor Towns during the Fall '08 term at Purdue University-West Lafayette.

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23,24 - Chem 11500 Lectures 23-24 Reading: 12.6 1 This Week...

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