P11 - - 4 r = a 3 HCP : Hexagonal Closest Packing- CN = 12-...

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Metals and Ceramics : * Bond Strength of ionic bonds increases as valency increases - Strongest ionic bond are formed between group I and group VII - Next strongest is between group II and group VI Important Metal Structures FCC : Face Centered Cubic - CN = 12 - High density - High atomic packing factor APF = Volume of atoms Volume of unit cell ae è ç ö ø ÷ ; 74% - 4 r = a 2 BCC : Body Centered Cubic - CN = 8 - High symmetry - Less dense packing - APF is 68%
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Unformatted text preview: - 4 r = a 3 HCP : Hexagonal Closest Packing- CN = 12- High density- High APF; 74%- More covalence than FCC SC : Simple Cubic- Low density- Low APF; 52%- 2 r = a Bond Type Bond Energy(Kcal/mole) Melting point Elastic Modulus(psi) Ionic *- Al 2 O 3 361 2200C Covalent- Si 84 1420C SiC 283 2600C Metallic- Fe 97 1530C Al 74 660C Cu 81 1080C 50 x 10 6 30 x 10 6 30 x 10 6 30 x 10 6 10 x 10 6 17 x 10 6...
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This note was uploaded on 03/21/2011 for the course CHE 332 taught by Professor Gregory during the Spring '11 term at Rhode Island.

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