Sodium chloride, commonly known as table salt, is a pure substance. In chemistry, the term "salt" is a reference to a variety of compounds formed in the reaction of a base and an acid. Compounds are considered to be pure substances.
A compound is formed when two or more atoms of different elements are chemically bonded together in a specific ratio. These chemical bonds cannot be broken with the use of physical force. Sodium chloride, when being processed for table salt, sometimes has anti-caking agents, such as calcium silicate, added. Potassium Iodide is sometimes added in the manufacturing of iodized salt.