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Chemistry LibreTexts

9: Ionic and Covalent Solids - Energetics

  • Page ID
    183352
  • Learning Objectives

    • Understand the geometric basis of radius ratio rules.
    • Understand the chemical basis of structure maps and why they are better predictors of crystal structures than radius ratios.
    • Use the Born-Mayer and Kapustinskii equations to calculate lattice energies of known and hypothetical compounds.
    • Construct Born-Haber cycles using lattice energies and calculate unknown quantities in the cycles.
    • Predict the stabilities of low and high oxidation states using lattice energies.
    • Understand the quantum mechanical origin of the extra "resonance" stability of metals.
    • Predict trends in the solubility and thermal stability of inorganic compounds using lattice energies.

    In Chapter 8, we learned all about crystal structures of ionic compounds. A good question to ask is, what makes a compound choose a particular structure? In addressing this question, we will learn about the forces that hold crystals together and the relative energies of different structures. This will in turn help us understand in a more quantitative way some of the heuristic concepts we have learned about in earlier chapters, such as hard-soft acid-base theory.