The first syllable of fluorine rhymes with FLOOR. As in FLOOR-een.

But it really ought to rhyme with FLEW. As in FLEW-reen.

I know, people look at you funny if you say FLEW-reen instead of FLOOR-een. But the “u” comes before the “o” doesn’t it? Try typing “flourine” in your word processor or a search box! I used to teach chemistry and I can assure you that fluorine is the single most misspelled word in the class. In fact I had to say FLEW-reen just to remind students of the goofy spelling.

Fluo is the first person singular (in the present tense) of the Latin verb fluere so we can blame the u-before-o mess on the damn Romans. The variety of English forms that emerged from fluo, fluere, fluxi, fluxum* is astonishing: fluid, fluent, flume, fluvial, fluctuate, flux, fluorescent, affluence, confluence, influence, effluvium, reflux, influenza, superfluous, and so on.

Fluorine is the devil’s spawn. It is the most reactive of all elements. Small amounts are deadly. It also burns but cannot be put out by ordinary firefighting methods. Both water and carbon dioxide merely feed the flame. The acid it makes—HF or hydrofluoric—is terribly corrosive and requires special handling and storage. It is one of the serious “bad boys” of industrial chemicals.

But because of this reactivity fluorine finds itself in many, many compounds. And it has uses in almost every industry. Did you know that Prozac is a fluorine compound? Its generic name is fluoxetine and it has the hideous official name of (R,S)-N-methyl-3-phenyl-3-(4-(trifluormethyl)phenoxy)propan-1-amine.

Fluorine makes the common inorganic salt sodium fluoride. We are very familiar with this stuff. It is in our toothpastes and mouthwashes. If we are lucky we have fluoride added to our water supply. Most of us have been consuming it all of our lives. Fluoridated water is one of the great public health success stories. People who consume fluoride in their water have healthier teeth. By a BIG margin! Don’t listen to pinheads who think fluoridation is bad. They are stupid. Wish them luck on their next “cleanse and detox” regime and hope it flushes out their heads.

In the meantime, enjoy all those beautiful smiles out there. And don’t forget to floss.

*Latin verbs are known by their four so-called “principal parts” of which the second is the infinitive.