PURPOSE: Set of two simple crystal models.

DESCRIPTION: The following crystals are modeled here, from left to right: (1) face-centered cubic, such as common salt, where sodium is black and chlorine is white, (2) an apparently indeterminate structure, which can nevertheless be studied for its symmetries.

SUGGESTIONS:

REFERENCES: (PIRA 1R50.20)

EQUIPMENT: Three crystal models.

SETUP TIME: None.