1. How does the inclusion of the Madelung constant improve the accuracy of the simple electrostatic model when it is used to predict the lattice energy of an ionic solid?

2. State Hooke’s law. Giving suitable examples, discuss the two main factors affecting the magnitude of stretching vibrations observed in infrared spectroscopy.

3. What are the main assumptions and limitations of the simple electrostatic model (based on Coulomb’s law) when it is used to predict the lattice energy of an ionic solid?