LESSON 4 · Reactions All Around You
Crystals You Use Every Day
Table salt is a crystal of sodium and chloride ions in a cubic lattice. Sugar crystallizes in a monoclinic structure.

Silicon crystals are the foundation of computer chips. Semiconductor manufacturers grow perfect single crystals of silicon weighing hundreds of kilograms, then slice them into wafers. Quartz crystals vibrate at precise frequencies when electrically stimulated, which is how watches keep time.