Ionic crystals are crystalline structures that grow from ionic bonds and are held together by electrostatic attraction. Ionic bonds are atomic bonds created by the attraction of two differently charged ions. The bond is typically between a metal and a non-metal.
The most prevalent ionic crystal example is table salt, NaCl. Other examples include:
Many of these look familiar? These examples show how ionic crystals are a part of our everyday lives.
As solids, ionic crystals are insulators. As Encyclopedia Britannica states:
"In insulators, nearly all the electrons are bound, and very few electrons are capable of carrying current. A typical metal has one or more conduction electrons in each atomic unit cell, a semiconductor may have only one conduction electron for each thousand unit cells, and an insulator may have one conduction electron per one million or one trillion unit cells."
Other key features of these ionic crystals are:
The crystalline structures form after the bond is created and the structure varies based on the ions which have combined.