Congruent and coordination numbers the equilibrium

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Unformatted text preview: needed. The bond-energy curve for material B exhibits a smaller radius of curvature than does A. Hence, it has the higher modulus and should be selected for this application. b. The component must operate at high temperatures. Since bond strength is related to the depth of the bond-energy well, we again select material B. c. This application requires a material with a high value of t h . Since t h increases as the asymmetry of the bond-energy curve increases, we select the material with the more asymmetric bond-energy well. The better choice for this application is material A. ....................................................................................................................................... conformation The arrangement of the rotatable bonds v within a molecule. congruent AND COORDINATION NUMBERS The equilibrium melting reaction 2.6 ATOMIC PACKING melting that occurs when a solid phase properties of to a liquid As demonstrated above, several important macroscopictransforms materials can be estimated on phase having identical composition. the basis of only a knowledge of the atoms present, the type of bonding between atoms, and the shape of the bond-energy curve. Other properties, such as density, coordination number The number section we discuss the largely depend on the arrangement of the atoms in the solid. In thisof nearest factors that influence the three-dimensional packing of atoms. ion. neighbors that surround an atom or The arrangement of atoms within a solid can be principally characterized by the core band number of nearest neighbors, orA band of number (CN), of eachlevels that is coordination electron energy atom in the structure. In turn,(usually) completelyisfilled and is located closer to the the coordination number influenced primarily by the type of bonding present and by the relative sizes of the atoms or ions. nucleus than either As valence Section 2.4.1, each ion can Consider the ionic compound CsCl. thediscussed in or conduction bands. be approximated as a hard sphere. Be...
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This note was uploaded on 02/25/2013 for the course PHYS 2202 taught by Professor Sowell during the Spring '10 term at Georgia Institute of Technology.

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