Material Science Final Exam Study Guide

Material Science Final Exam Study Guide - Material Science...

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Unformatted text preview: Material Science Final Exam Study Guide Introduction Classification of Materials. General Properties Metals Closed Packed High strength high toughness highly conductive Ceramics Ionic or covalent bond poor conductive high temperature resistance 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 Atomic Structure and Bonding 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 Relates thermal properties with measurable variables (P, T, composition) G<0 then the reaction proceeds Kinetics Reaction and rates determine the properties Arrhenius Equation 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 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 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 and atomic packing Coordination number=r/R r=radius of cation R=radius of anion CN=2 0<r/R<.155 CN=3 .155<r/R<.225 CN=4 .225<r/R<.414 CN=6 .414<r/R<.732 CN=8 .732<r/R<1 CN=12 r/R=1 Atomic Packing Crystalline Materials Short and Long Range Order Amorphous Materials Short Range Order Difference between thermosets and thermoplastics Thermosets Polymers that typically do not melt easily (rigid rubber) Polymer bonds chains with covalent bonds Thermoplastics Polymers that include secondary bonds such as H-bonds Low melting points Crystal Structures Difference between short and long range order...
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This note was uploaded on 05/02/2008 for the course CHE 253 taught by Professor Carrion during the Fall '08 term at University of Louisville.

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Material Science Final Exam Study Guide - Material Science...

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