Key Facts for Quiz #1

Key Facts for Quiz #1 - Key Facts: Lecture 1:...

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Key Facts: Lecture 1: Semiconductors: Ceramic materials with electrical properties between conductors and insulators. Metals: - Dense - Electrical conductors - Heat conductors - Shiny appearance - Strong - Malleable - Sometimes magnetic Ceramics: - Poor thermal/electrical conductors - Stable/inert - Hard - Brittle - Transparent or opaque Polymers - Variety of properties - Low densities - Non-conductor - Low melting point - Can be very flexible Composite - More than one material type Other stuff: - Adding impurities to an atom increases resistivity. - Deforming atom increases resistivity. - Structure affects optical properties i.e. can be transparent, translucent, or opaque, depending on structure. - Examples of processing: casting, sintering, vapor deposition, doping, forming, jointing, annealing. Lecture 2: Interatomic Forces: attractive and repulsive: Equilibrium when Fnet = 0 PE Curve – E is at a minimum when Fnet = 0. - Deeper well = more bond energy - Potential well minimum corresponds to equilibrium spacing/bond length - Thermal expansion is due to asymmetry in well shape. - Depth of well corresponds to max bond energy. Electronegativity: varies from, 0.8 (Fr) to 4.0 (F) Ionic Bonding: - Hard - Non-conducting - brittle
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- thermal insulator - large electronegativity differences, Covalent Bonding: - comparable electronegativities - directional and strong - hard
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This note was uploaded on 05/01/2008 for the course MAT 33 taught by Professor Keith during the Spring '07 term at Lehigh University .

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Key Facts for Quiz #1 - Key Facts: Lecture 1:...

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