Sphere packing as models of crystal structures
Use spheres to build models for the simple cubic (sc), body centred cubic
(bcc), face centred cubic (fcc) and hexagonal closed packed (hcp) lattices.
These are basic structure types of metals. The spheres are also used
to model the structure of salts. Since sodium chloride is one of
the common and important salt, you construct this structure to get
a 3-dimensional feeling of this structure.
The use of spheres as models for these structures is a brilliant scientific
method. Using these spheres you can do the following:
These are also goals of the lectures on the following topics:
- Distinguish sc, bcc, fcc, and hcp structure types.
- Correlate the radii of spheres with edge lengths of the unit cells.
- Demonstrate the tetrahedral and octahedral sites created by sphere packings.
- Calculate the radii of spheres that will fit exactly into the octahedral and
tetrahedral sites of closest packed spheres.
- Describe the crystal structure of NaCl