Properties of Fluorine and Fluoride

The element fluorine has nine protons, ten neutrons, and nine electrons, giving a mass of 19 Da. Fluorine is the smallest halide element (Sect. 1.1.5) and it forms a gas that is so electron deficient that it has all reacted with metals and only its ions (F 1) are found on earth. Fluoride and hydroxide ions have almost the same mass, 19 Da and 17 Da respectively. Because fluoride is more electronegative, it replaces the hydroxide ion on crystals without altering their overall structure. This type of alteration is referred to as an isomor-phous ion replacement. 

How Mottled Enamel Relates to Fluoride in the Water Supply 

At the same time, McKay was informed of an outbreak of mottled enamel in children who lived in Bauxite, a town near Colorado Springs. Bauxite was named for large deposits of bauxite, which the Aluminum Company of America (ALCOA) mined there. Children who drank spring- or shallow-well water had normal teeth, but children drinking deep-well water had severe enamel mottling. In 1931, ALCOA s chief chemist, 

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