bq1-2009key - (1 point) What is the coordination number...

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PRINT NAME ___________________________________ INTRODUCTION TO MATERIAL SCIENCE MSE-150 BONUS QUIZ 1 I PLEDGE MY HONOR THAT I HAVE NEITHER GIVEN OR RECEIVED AID ON THIS EXAMINATION. SIGNATURE ____________________________________ The diamond cubic crystal structure can be described as an FCC arrangement of atoms with additional atoms in 4 of the 8 tetrahedral interstitial sites. (1 point) How many carbon atoms are associated with a unit cell for the diamond cubic structure? a) 2 b) 4 c) 6 d) 8 (1 point) What is the coordination number for diamond cubic? a) 2 b) 4 c) 6 d) 8 (1 point) Describe the chemical bonding in diamond cubic. a) ionic b) covalent c) ionic/covalent d) covalent/ionic (1 point) Which of these elements form the diamond cubic structure? a) Tin b) Arsenic c) Silicon d) Zinc (3 points) If carbon has an atomic radius of 0.0770 nm, calculate the lattice constant for diamond. a) 0.368 nm b) 0.468 nm c) 0.356 nm d) 0.668 nm The III-V compound semiconductor, GaAs, has the crystal structure of α -ZnS (S atoms in a FCC arrangement and Zn atoms in 4 of the 8 tetrahedral interstitial sites)
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Unformatted text preview: (1 point) What is the coordination number (i.e., number of nearest neighbor atoms) in this structure? a) 2 b) 4 c) 6 d) 8 (1 point) How many atoms Ga atoms per unit cell? a) 2 b) 4 c) 6 d) 8 (1 point) How many atoms As atoms per unit cell? a) 2 b) 4 c) 6 d) 8 (1 point) Describe the chemical bonding in GaAs a) ionic b) covalent c) ionic/covalent d) covalent/ionic (3 points) If the electronegativity of Ga is X Ga = 1.8 and As is X As = 2.2, calculate the percentage of ionic character of the chemical bond in GaAs. % ionic = (1 e 1/4(Xga Xas)^2 ) x 100 a) 4% b) 6% c) 10% d) 18% (3 points) Calculate the lattice constant (a) for GaAs in nm (r Ga = 0.126 nm and r As = 0.120 nm). a) 0.3681 nm b) 0.4681 nm c) 0.5681 nm d) 0.6681 nm (3 points) Calculate the density of GaAs (g/cm 3 ) (AW Ga = 69.72 g/mole, AW As = 74.96 g/mole, 6.023 x 10 23 atoms/mole) a) 4.241 g/cc b) 5.241 g/cc c) 6.241 g/cc d) 7.241 g/cc...
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