HW 2-Sol - Homework #2 solution For a molecule of NaCl E =...

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Homework #2 solution For a molecule of NaCl 12 6 2 12 12 6 4 14.4 3 3 5.14 3.71 4(0.0062) Na Cl ke z z EI E rr r σσ ε ⎡⎤ ⎛⎞ ⎛⎞ =−+ + ⎢⎥ ⎜⎟ ⎜⎟ ⎝⎠ ⎝⎠ ⎣⎦ =−−+ From , 0 = dr dE using maple, 0 3069 . 2 A r For a crystal of NaCl 12 6 2 12 1 2 12 6 () 4 14.4 *1.75 3 3 5.14 1.43 4 * 6 2 n N ασ σ + + =−− +⋅ From , 0 = dr dE using maple, 0 2.55 A The interactions among all ions in the crystal tends to screen out ionic bonding so atomic bonds are longer (cohesive energy is less negative) Ionic Covalent Metallic 1. Coulomb interaction 2. Non-directional 3. Poor thermal & electrical conductivity 4. strong bonds 5. High melting T 1. Sharing valence electron 2. Directional 3. semi-conductivity 4. mostly week bonds 5. relatively low melting T 1. sea of electron 2. Mostly non-directional 3. Good conductivity 4. Moderate bonds 5. relatively High melting T
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C S V V APF = = cell unit of Volume atom Volume * Atom of Number Single cubic 3 3 4 * 1 r V S π = , 3 ) 2 ( r V
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This note was uploaded on 12/10/2010 for the course MSEN 601 taught by Professor Zhang during the Spring '08 term at Texas A&M.

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HW 2-Sol - Homework #2 solution For a molecule of NaCl E =...

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