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Material Science Test 1 Study Guide

Material Science Test 1 Study Guide - Material Science...

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Material Science Study Guide Classification of materials (Based on atomic structure and engineering properties: mechanical, chemical, magnetic, optical, ect.) Metals Closed Packed High strength, high toughness large amount of electrons--highly conductive Ceramics Ionic or covalent bond poor conductive high temp, high corrosion resistance Polymers large segments joined together forming a huge molecule called macromolecule light weight low strength can be conductive Composites made of two different materials can mix materials to get the best properties from each material Semi conductors covalent bond conductive bond can absorb and emit light Electronic configuration of elements 1s-2s-2p-3s-3p-4s-3d-4p-5s-4d-5p-6s-4f-5d-6p-7s-5f-6d Valence electrons and electronegativity Valence Electrons Electrons in the outermost shell Electronegativity Tendency of an atom to attract electrons Explain how thermodynamics and kinetics determine if an event is possible Thermodynamics Energy
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Relates thermal properties with measurable variables (P, T, composition) ∆G<0 then the reaction proceeds Kinetics Reaction and rates determine the properties Arrhenius Equation (memorize) K=C exp(-Q/RT) K=reaction rate C=constant Q=activation energy (J/mol) R=Ideal gas constant (8.314 J/mol*K) T=absolute temp Types of Bonds Primary (determines properties of metal and ionic materials) Ionic (transfer of electrons from a electropositive to a electronegative atom) Covalent (shares electrons, only happens on electronegative elements, elements with a valence of 4 or more, and carbon based compounds) Metallic (happens on electropositive elements, having valence electrons of 3 or less, electrons will form a cloud of electrons surrounding positive cores, electrons delocalized) Secondary (determines properties of polymers) Does not involve electron transferring or sharing One or more orders of magnitude, weaker than primary bonds Form dipoles Van der Waals-temporary bond Hydrogen Bonding-permanent bond Bond Energy Curve How does it determine material properties bond energy average bond length elastic modulus (measures the resistance of any material) thermal expansion coefficient How to calculate coordination numbers Coordination number=r/R r=radius of cation R=radius of anion CN=2 0<r/R<.155 CN=3 .155<r/R<.225
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CN=4 .225<r/R<.414 CN=6 .414<r/R<.732 CN=8 .732<r/R<1 CN=12 r/R=1 Difference between thermosets and thermoplastics
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