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Crystal Structures is one of the most colorful and exciting modules. The seven crystal systems are modeled and presented so that the user can clearly see the similarities and differences between the systems. Bravais Lattices for the cubic system are demonstrated. We include ball and stick models as well as space-filling representations to prepare the student for closest-packed structures and ionic lattices. The program allows the user to expand, rotate, and construct representative ionic and metallic crystal lattices. The concepts of radius ratio and methods for determining stoichiometry from lattice structures allows students to visualize and understand the structure of ionic salts.

Crystal Structures Quiz contains exercises for the student that examine all of the material in Crystal Structures. For instance, the student is asked to work backward from the lattice to determine the system to which a crystal belongs. Other problems question the number of atoms and the coordination number of each atom in a unit cell. The final exercises involve determining or identifying the coordination numbers of component ions, the types of holes the ions occupy, the lattice structures of the ions, and the correct stoichiometry of the salt for several ionic lattices. While this module is demanding it is also rich with hints and explanations.

http://www.cem.msu.edu/~gencem/cryst/index.html