9. Fluorine: Tyger Tyger, Burning Bright

Just try to tally the body count behind the periodic table’s most reactive element, and learn why it’s good for your health.

Featured above: Henri Moissan working his apparatus to isolate fluorine in 1886.

Not James Hetfield: It took a long time for anyone to update Pliny’s take on the elements, but after that, it took several more centuries for De Re Metallica to be translated into English. The first person to do so was then-engineer and future U.S. President Herbert Hoover, with assistance from his wife, Lou Henry.

“Halogen,” by the way, is a word that means “salt-former,” because of Group 17 elements’ tendency to, well, form salts. If that doesn’t make a ton of sense right now, it will when we get to sodium.

A Little Goes A Long Way: Our nameless, hapless victim died from a truly small amount of hydrofluoric acid. If you don’t have a solid reference for how much liquid 100ml is, we’re talking about the jar on the right:

It’s Not That Bad, It’s Worse: As acids go, hydrofluoric acid is not a particularly strong one. An acid’s strength is labeled on the pH scale, a measure of how many hydrogen ions it will release when in contact with another substance. This is the “hydro” of hydrochloric and hydrofluoric acids, as well as what the “H” stands for in “pH.” Hydrofluoric acid is no slouch, but there are plenty of other acids that do a better job of donating hydrogen ions. It’s the second half of hydrofluoric acid that makes it so hazardous: that highly reactive fluorine. While acid can cause burns that are highly dangerous, fluorine will go deeper and works on a longer time scale.

It’s Nice They Didn’t Need It: In this episode, I mention briefly the possibility that Neil Armstrong and Buzz Aldrin might not have returned from the Moon. In 1969, this was anything but unthinkable — this was a known and ultimately acceptable risk.

President Nixon’s speechwriter, William Safire, prepared a speech called, “In The Event Of Moon Disaster.” It’s a little surprising that this was eventually made public knowledge, but I think we’re all better for it. Benedict Cumberbatch performed a reading of the speech:



Click To Read Transcript





  1. Fatality Due To Acute HF Exposure. Joseph Kwan, Director, Health, Safety and Environment Office, University of Vermont. Backed up on this site for archival purposes.
  2. The Royal Society of Chemistry, Fluorine, An Obsession With A Tragic Past. Richard Toon, September 2011.
  3. Humphry Davy: Poet And Philosopher, p. 174. Sir Thomas Edward Thorpe, 1896.
  4. Science History Institute, Not-So-Great Momens In Chemical Safety. Mark Michalovic, Summer 2008.
  5. The Story Of Chemistry, Anne Rooney.
  6. Lateral Science, The Tiger Of Chemistry.
  7. CDC, Achievements In Public Health, 1900-1999: Fluoridation Of Drinking Water To Prevent Dental Caries.
  8. Chemistry World, Fluorine Finally Found In Nature. Neil Withers, July 11, 2012.

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