Ammonium chloride

The ceasium chloride structure is usually adopted by ions which are similarly sized. One exception to this is ammonium chloride:

This is possible because the ammonium cation can form hydrogen bonds to the chloride anions.

Ammonium chloride is a white powder. Its mineral form sal ammoniac was known to the ancients, called "salt of Amun" because it was found near the temple of Amun in Libya.

When heated it decomposes to ammonia and hydrochloric acid. You can also extract ammonia from it by reacting it with a strong base.

It is sometimes added to food as a flavoring agent for licorice, or to give cookies a crisp texture.