18. Argon: More Than Meets The Eye

Today’s element gets called “lazy,” but that’s actually a terrible misnomer.

Featured above: Two honor guards watch over the Declaration of Independence and some high-quality argon.

Show Notes

Good Reads: The Eye of Argon can be read in its entirety here, and I recommend that everyone do so.

Return of Ramsay and Rayleigh: Argon was discovered by the same two guys who discovered neon, actually, a few years earlier. Argon was the easy one to discover, since it makes up one full percent of the Earth’s atmosphere. They would go on to discover krypton and xenon, too, all within a few weeks of each other. But we’ll try to find time for their story when we get to those elements.

Weight Problem: One thing you might have noticed is that, as we traverse the periodic table, each element has weighed more than the last one. This makes sense: The elements are arranged by atomic number, which denotes how many protons are in its nucleus. Usually, the number of neutrons is commensurate with that increase in protons.

Argon, however, weighs more than the next element, potassium. Element 18 has an atomic mass of 39.948, while element 19 has an atomic mass of 39.098. This is because the atomic mass is calculated by averaging the mass of each isotope of an element, by its abundance. There happen to be more isotopes of heavy argon on Earth, and more isotopes of light potassium. It’s a weird quirk, but this means that on average, on Earth, argon weighs more than potassium.

More Of A Treasure Protector: The Declaration of Independence (and Constitution) is protected by more than just bulletproof glass and inert gas. Each night, the documents are lowered into a 50-ton vault that is fireproof, waterproof, and atom-bomb-proof. Two guards keep watch over the documents and can activate the mechanism whenever they think they’re in danger.

I’d Still Rather Eat Them: In 1981, the day after Thanksgiving, Rangaswamy Srinivasan brought his leftovers to work. He had important work to do: Shoot lasers at the bird. You can read more about that here, but the short version is, that led directly to LASIK surgery. (The work done by L’Esperance had more to do with complications from diabetes.)

Really did have a view of central park

Pew Pew: Regarding modern laser weaponry, it’s surprisingly sophisticated and impressive. Take Raytheon’s own High-Energy Laser Weapon System:

In this video, it accurately tracks and quickly destroys a tiny quadcopter. In their own words, this weapon “Identifies, tracks, and defends against enemy missiles, mortars, unmanned vehicles, swarming boat attacks and other ‘close-in’ defense situations. They provide precise, clean, low-cost engagements with near-infinite magazines.”

It’s all fun and games until someone gets hurt, which, actually, is exactly the kind of situation this is intended for.

Store Your Documents In A Cool, Dry, Dark Place: Might I recommend Garth Marenghi’s Darkplace?


Episode Script

The Eye Of Argon, by Jim Theis.

The weather beaten trail wound ahead into the dust racked climes of the baren land which dominates large portions of the Norgolian empire. Age worn hoof prints smothered by the sifting sands of time shone dully against the dust splattered crust of earth. The tireless sun cast its parching rays of incandescense from overhead, half way through its daily revolution. Small rodents scampered about, occupying themselves in the daily accomplishments of their dismal lives. Dust sprayed over three heaving mounts in blinding clouds, while they bore the burdonsome cargoes of their struggling overseers.

“Prepare to embrace your creators in the stygian haunts of hell, barbarian”, gasped the first soldier.

“Only after you have kissed the fleeting stead of death, wretch!” returned Grignr.

A sweeping blade of flashing steel riveted from the massive barbarians hide enameled shield as his rippling right arm thrust forth, sending a steel shod blade to the hilt into the soldiers vital organs. The disemboweled mercenary crumpled from his saddle and sank to the clouded sward, sprinkling the parched dust with crimson droplets of escaping life fluid.

The enthused barbarian swilveled about, his shock of fiery red hair tossing robustly in the humid air currents as he faced the attack of the defeated soldier’s fellow in arms.

“Damn you, barbarian” Shrieked the soldier as he observed his comrade in death.

I would love to continue, but there are 22 more pages, and we’re supposed to be talking about chemistry.

The Eye Of Argon was published in 1970 when the author was only 17, and while it is an incredible work that deserves any excuse for a dramatic reading, it has nothing to do with element 18 of the periodic table. The titular Eye of Argon is a “scarlet emerald” set in a golden idol that appears in chapter three and a half.

A narrator with less appreciation for the writing process might be tempted to draw more of a connection between the story’s title and the subject of today’s episode. You see, the element earned its name due to its chemical inertness, coming from the Greek word “argos,” which means “lazy.”1

I believe accusing Theis of laziness would be inaccurate. But sometimes, there is no justice: As we’ll see today, argon itself is no slouch, either.

You’re listening to The Episodic Table Of Elements, and I’m T. R. Appleton. Each episode, we take a look at the fascinating true stories behind one element on the periodic table.

Today, we’ll go on about argon.

It would be easy to give short shrift to argon. It lacks both the household name recognition of fellow group members helium and neon, and the exotic cachet of its downstairs neighbors krypton, xenon, radon, and oganesson. If it’s known for anything, it’s as a blue light special version of neon — literally. When a current is applied to argon, it demonstrates the same luminous behavior as neon, but with a cool blue hue, rather than a “blaze of crimson light.”

This is, of course, because of argon’s full valence shell, which also lends it that chemical laziness it’s named for. But being inert doesn’t make argon uninteresting. In fact, that’s the reason it tends to wind up in so many interesting places, like arc-welding workshops, dry suits for scuba divers, and the National Archives of the United States.2

That last case is particularly interesting. Argon fills the display case that houses the Declaration of Independence, guarding against the oxidizing effects of the ambient atmosphere. But archivists haven’t always taken such effective precautions to preserve these historical documents.3

Originally, this was a matter of necessity. Declaring all that independence helped start a war, after all, so the document was dragged around by the Continental Congress as it traveled. The Declaration was similarly transported during the War of 1812, so less than 50 years after the country’s founding, it was already looking pretty ragged.4

Some folks had the idea to make a few certified copies of the document, hoping that would lessen demand for the original. A good idea, but at some point in that process, it seems that someone spilled water on the document.

The original evaded further harm for nearly twenty years after that. In 1841, someone dug it out of storage and thought, “This would look great on the wall of the US Patent Office.”

Whoever this person was, at least they cared enough to frame it before hanging it on the wall of a room that received lots of natural sunlight. That’s great for a living room, but very bad for a historical document.

Remember how sunlight was the best bleach people had before chlorine? Well, the Declaration of Independence stayed on that wall for decades. Every once in a while, someone would notice that the ink sure seemed to be fading, but it stayed right there until 1876.

To celebrate the country’s centennial, the document was brought to Philadelphia for citizens to admire. It didn’t receive anywhere near the kind of care it deserved until 1894, when it was removed from public display.

A few years later, it was moved to Fort Knox, and finally started to see the sort of treatment a historical document deserves. Today, it’s back on public display, but with much more protection: Special bulletproof glass keeps out even the minuscule amount of light that’s present in the National Archives, and of course, the airtight case is full of inert gas.

Until quite recently, that gas was helium. It’s just as inert as any other noble gas, but more expensive to acquire, with an unfortunate tendency to escape the container, since helium atoms are so very small.

So in 2003, the case was pumped full of element 18, and all the helium atoms argon.

As we know, a chemically inactive substance can still be quite reactive to other kinds of stimuli. Like we discussed in episode 10, when neon is supplied with electrical energy, those neon atoms briefly enter an “excited” state, then release that energy as light.

This property can be exploited for more than the common neon sign. If you line things up just right, you can get something considerably more powerful.

By pumping an argon chamber full of electricity, and surrounding that chamber with mirrors, you can create a kind of Light Amplified by the Stimulated Emission of Radiation: A laser.5

A laser has three chief properties that separate it from the kind of light we normally encounter.

First of all, it’s monochromatic, emitting light of one very specific wavelength. There are lasers made with all kinds of materials that create different colors; argon lasers create a deep blue.

A laser also stays tightly focused, or collimated, unlike the light emitted by, say, a flashlight, which falls off and gets fuzzy over a short distance.

Finally, laser light is coherent. That is, all the photons are moving in the same direction, in lockstep with one another.

These three characteristics allow lasers to be used in all sorts of ways that mundane light cannot; everything from light-speed communication, to laser cutting and welding, to more accurate weather predictions, and much more.

Since it focuses all that energy onto such a small spot, you never want to point a laser at someone’s eye — unless you’re explicitly qualified to do so. Lasers can severely damage sensitive tissues like eyes, but if wielded carefully, that same power can correct vision problems and cauterize wounds inside the eyeballs.

Dr. Francis L’Esperance, in New York City, was the first ophthalmologist to use lasers in this way.6 In the late 60’s, military contractor Raytheon had constructed an argon laser for the US government, which they intended to test as a weapon. But by the time Raytheon had built the thing, the government decided they’d like to have a laser that fires beams in the classic red, rather than argon’s blue. Left holding the bag, Raytheon figured it was better to sell it rather than let it collect dust, and L’Esperance was the buyer.

But there was a problem. Since the laser was built with a decidedly non-civilian purpose in mind, the designers didn’t consider things like whether it could fit in a freight elevator. At three-and-a-half meters long, it could not, and L’Esperance’s office was on the ninth floor.

That’s all right — there was still the window. So L’Esperance hired the best rigger he could find, who set up a series of pulleys and cables to deliver the payload. A pretty big crowd gathered to watch. It must have been quite a sight to see an enormous laser gun lifted high into the air like that. But the spectacle became a minor disaster when something snapped, and the machine crashed to the ground.7

L’Esperance must have thanked his lucky stars that he had taken out insurance on the laser, because it paid enough for Raytheon to build him a new one. Yet there still remained the problem of exactly how to get the massive thing up to the ninth floor.

Fortune smiled upon L’Esperance yet again. By the time the new laser was delivered, a construction crew was conducting renovations nearby. L’Esperance slipped $25 to the site’s crane operator, and in turn, the crane operator slipped the package right through the window.8

L’Esperance used that laser to conduct pioneering research, leading to medical procedures that have helped millions of patients. And he managed to do it without giving up his priceless ninth-story view of Central Park.

Raytheon and other vendors continue researching laser weaponry to this day, but argon has already been part of militaries’ arsenals for decades.9 Heat-seeking Sidewinder missiles employ compressed argon gas as a coolant while the projectile flies two-and-a-half times the speed of sound. Conservatively, tens of thousands of these missiles have been produced, so it should be pretty easy to find one when adding argon to your element collection.10

If, for some reason, you run into obstacles during this endeavor, there are more mundane sources for element 18. It’s often used as an effective insulator in double-hung windows, so it’s possible that you kind of have a display case full of the stuff already.

But you can probably find with ease a small glass ampule filled with argon. They used to be pretty common. They just weren’t marketed as such.

Incandescent light bulbs are the kind that work by passing an electric current through a filament until it glows white-hot. Compact fluorescent bulbs are more common these days, but you can still find the older style sold to hipsters as “Edison Bulbs,” or maybe in your parents’ linen closet.

Those bulbs need to be vacuum-sealed, because if ambient air were to get inside, the filament would quickly burn up — or “oxidize,” as we’ve learned it — and become useless. But the bulbs aren’t devoid of all atmosphere. Instead, they’re filled with argon to keep the air pressure inside roughly similar to the air pressure outside the bulb. Since argon is inert, the filament is safe.

That bulb would also make for a charming way to display tungsten, since that’s what the filament is most likely made of. But let’s not get ahead of ourselves. We have 56 more episodes to go before we need to worry about that.

Thanks for listening to The Episodic Table of Elements. Music is by Kai Engel. To learn about argon’s discovery and what’s so weird about how much it weighs, visit episodic table dot com slash A R.

Next time, we’ll go bananas for potassium.

This is T. R. Appleton, reminding you to store your priceless historical documents in a cool, dry place.


  1. LiveScience, Facts About Argon. Stephanie Pappas, February 20, 2015.
  2. Chemistry World, Argon. John Emsley, May 12, 2010.
  3. Wired, July 4, 1776: Preserving The Declaration. Tony Long, July 2, 2009.
  4. The Edge Of The American West, The Declaration Of Independence And The Constitution In Storage. December 23, 2009.
  5. Professor Mark Csele’s Homebuilt Lasers Page, Argon Ion Lasers.
  6. Columbia University Department Of Ophthalmology, Milestones.
  7. The History Of The Laser, p. 274. Mario Bertolotti, 1999.
  8. Optics & Photonics News, History Of Gas Lasers, Part 1 — Continuous Wave Gas Lasers. Jeff Hecht, January 2010.
  9. Raytheon: Laser Solutions.
  10. Air Power Australia, The Sidewinder Story. Carlo Kopp, 1994, 2005, 2010.

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