QUIZ2-2009key

QUIZ2-2009key - character is more covalent than ionic F...

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PRINT NAME ________________________ INTRODUCTION TO MATERIAL SCIENCE MSE-150 QUIZ 2 I PLEDGE MY HONOR THAT I HAVE NEITHER GIVEN OR RECEIVED AID ON THIS EXAMINATION. I FURTHER PLEDGE THAT, IF I HAVE REASON TO SUSPECT THAT THE CODE HAS BEEN VIOLATED, I HAVE TAKEN OR WILL TAKE ACTION AS OUTLINED IN THE CODE. SIGNATURE _________________________ (1 point each) True or False Ionic bonding is a directional primary bond resulting from electrostatic forces. F Covalent bonding is a directional primary bond resulting from sharing of delocalized valence electrons. F Anions are typically larger than cations. T 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). T 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. T As the difference in the electronegativities between the elements in a ceramic compound increases the bond
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Unformatted text preview: character is more covalent than ionic. F Polymers typically contain both covalent and secondary bonding. T The non-directional nature of the metallic bond results in crystals with low coordination numbers. F (1 point each) Label the following as characteristics of strong bonds ( S ) or weak bonds ( W ). low melting point W short bond length S large thermal expansion coefficient W large elastic modulus S (3 points) What are the coordination numbers (number of nearest neighbors) for FCC, HCP, and body centered cubic (BCC) crystal structures? FCC CN = 12 HCP CN = 12 BCC CN = 8 (2 points) How many atoms are contained inside of the unit cell for FCC and BCC crystals? FCC 4 atoms/UC BCC 2 atoms/UC (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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