What are fluorides, hydrogen fluoride, and fluorine?
Fluorides, hydrogen fluoride, and fluorine are chemically related. Fluorine is a pale, yellow-green gas that has a strong, sharp odor. It combines with hydrogen to make hydrogen fluoride, a colorless gas. Hydrogen fluoride dissolves in water to form hydrofluoric acid. Fluorine also combines with metals to make fluorides like sodium fluoride and calcium fluoride, both white solids. Sodium fluoride dissolves easily in water, but calcium fluoride doesn’t. Fluorine is used in rocket fuels, glass, enamel, and bricks. Hydrogen fluoride is used mainly to make aluminum and chlorofluorocarbons (CFCs). Fluorides are used in making steel, chemicals, ceramics, lubricants, dyes, plastics, and pesticides (for ants and roaches). Toothpaste and mouth rinses have fluorides added to prevent cavities. If drinking water supplies are low in fluoride, many communities add fluorides to help prevent cavities. Some skin medicines and cancer treatment drugs also contain fluorides.
Fluorides are properly defined as binary compounds or salts of fluorine and another element. Examples of fluorides include sodium fluoride and calcium fluoride. Both are white solids. Sodium fluoride readily dissolves in water, but calcium fluoride does not. Sodium fluoride is often added to drinking water supplies and to a variety of dental products, including toothpastes and mouth rinses to prevent dental cavities. Other fluoride compounds that are commonly used for water fluoridation are fluorosilicic acid and sodium fluorosilicate. Calcium fluoride is the compound in the common minerals fluorite and fluorspar. Fluorspar is the mineral from which hydrogen fluoride is produced. It is also used in the production of glass and enamel and in the steel industry. In this profile, we will often use the term “fluoride” to include substances that contain the element fluorine. The reason for this is that we generally measure the amount of fluorine in a substance rather than the amount of a par
