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Unformatted text preview: T Polymers typically contain both covalent and secondary bonding. T The non-directional nature of the metallic bond results in crystals with high coordination numbers. (1 point each) Label the following as characteristics of strong bonds ( S ) or weak bonds ( W ). W low melting point S short bond length W low hardness S small thermal expansion coefficient W low elastic modulus (3 points) What are the coordination numbers (number of nearest neighbors) for FCC, HCP, and body centered cubic (BCC) crystal structures? FCC 12 HCP 12 BCC 8 (2 points) How many atoms are contained inside of the unit cell for FCC and BCC crystals? FCC 4 atoms BCC 2 atoms (3 points) Calculate the atomic radii for copper (FCC with a = 0.361 nm). Use the correct number of significant figures for the correct answer. a) 0.1565 nm b) 0.157 nm c) 0.128 nm d) 0.1276 nm...
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- Spring '07