Science, Tech, Math › Science What Is the Difference Between Fluorine and Fluoride? Share Flipboard Email Print Toothpaste contains fluoride, but not free fluorine. Westend61/Getty Images Science Chemistry Periodic Table Basics Chemical Laws Molecules Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated January 29, 2019 First off, it's fluorine and fluoride and not flourine and flouride. The misspelling is common, but the "u" comes before the "o" in both. Fluorine is a chemical element. In pure form, it is a highly toxic, reactive, yellowish-green gas. The fluorine anion, F-, or any of the compounds containing the anion are termed fluorides. When you hear about fluoride in drinking water, it comes from adding a fluorine compound (usually sodium fluoride, sodium fluorosilicate, or fluorosilicic acid) to drinking water, which dissociates to release the F- ion. Stable fluorides are also found in fluoridated toothpaste and mouthwash. Summary of the Difference Fluorine is an element. Fluoride either refers to the fluorine ion or to a compound that contains the element fluorine.