practicetestquiz2

# practicetestquiz2 - The non-directional nature of the...

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PRINT NAME ________________________ INTRODUCTION TO MATERIAL SCIENCE MSE-150 QUIZ 2 (1 point each) True or False Ionic bonding is a directional primary bond resulting from electrostatic forces. Covalent bonding is a directional primary bond resulting from sharing of delocalized valence electrons. Anions are typically larger than cations. The atomic packing factor (APF) of the face centered cubic (FCC) structure is the same as the APF of the hexagonal close packed structure (HCP). The difference between the FCC and HCP structures is the stacking sequence of the close-packed planes where FCC is ABCABC and HCP is ABAB. As the difference in the electronegativities between the elements in a ceramic compound increases the bond character is more covalent than ionic. Polymers typically contain both covalent and secondary bonding.
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Unformatted text preview: The non-directional nature of the metallic bond results in crystals with low coordination numbers. (1 point each) Label the following as characteristics of strong bonds ( S ) or weak bonds ( W ). low melting point short bond length large thermal expansion coefficient large elastic modulus (3 points) What are the coordination numbers (number of nearest neighbors) for FCC, HCP, and body centered cubic (BCC) crystal structures? FCC CN = HCP CN = BCC CN = (2 points) How many atoms are contained inside of the unit cell for FCC and BCC crystals? (3 points) Calculate the atomic radii for gold (FCC with a = 0.4078 nm). Use the correct number of significant figures for the correct answer. a) 0.1766 nm b) 0.1442 nm c) 0.177 nm d) 0.144 nm...
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