Let’s uncover element 57, and find out why the “rare earths” are neither rare nor earths nor an empire.
Featured above: The lanthanides and actinides taking their rightful place on the periodic table.
I do hope you’re all staying safe and healthy out there as we deal with a pandemic of truly historic proportions. I don’t know whether chloroquine will prove helpful or not, but it makes me wonder if a halogen element will once again serve public health in our hour of need.
But none of that has to do with today’s subject: the first of the lanthanides. (Or maybe not a lanthanide at all, but I’m not one to be that pedantic.)
Wheeliums Within Wheeliums: I hope I didn’t make the chain of discoveries too difficult to follow. It’s probably easier to grok in visual form. This graphic comes from Peter van der Krogt’s indispensable Elementymology website:
YouTube Begins To Learn At A Geometric Rate: Lots of cheekiness from the world’s most popular social video network lately. First, I saw that national treasure Weird Al Yankovic uploaded a concert video for Germs just a week ago. Very nice. (Also, is that song more of a parody of [NSFW] Terrible Lie, or [NSFW] Closer? Scholars continue to debate, but they all agree that he Nine Inch Nailed both the look and the sound.)
Then, immediately following that, ＴＨＥ ＡＬＧＯＲＩＴＨＭ recommended to me this video, featuring the hilarious David Mitchell. I was very impressed.
Today we begin our study of a new class of elements: The lanthanides. These constitute the top row of that island of elements that awkwardly hangs around the bottom of the periodic table.
These elements — the lanthanides, and the row below, the actinides — aren’t actually separate from the other elements on the table. The lanthanides, for instance, would fit quite neatly in between barium and hafnium, the same way the first row of the transition metals fits neatly between calcium and gallium.
The only problem is, if you actually placed the lanthanides in that spot, the periodic table would be twice as wide. Lest you think that’s no big deal, I’ll remind you that Alexandre-Émile Béguyer de Chancourtois drew up his Telluric Screw several years before Mendeleev had his dream, but his publisher found it too unwieldy to print.1
And while the justification for this detachment is aesthetic rather than scientific, it’s not entirely inappropriate that these oddities are set aside. Till this point in our series, it’s held true that elements that share a column display similar chemical behaviors. But these two series display great similarities across their horizontal rows — so much so that at first, they were all thought to be one metal.
So lets tease these elements apart to see exactly what separates them, starting with the lanthanest lanthanide of all: lanthanum.
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’re finding common ground with lanthanum.
Carl Gustaf Mosander was a professor at Stockholm’s Karolinska Institute during the early 19th century. In 1839, he got his hands on a mineral sample containing cerium — the next element in this series, which was discovered 36 years earlier by Mosander’s mentor, Jons Jakob Berzelius.2
The two of them were quite close. Mosander wasn’t just Berzelius’ assistant, but his successor as Permanent Secretary at the Stockholm Academy of Sciences, and he also lived with Professor and Mrs. Berzelius for many years.3
Mosander clearly had a lot of love for his role model, That might be why, when he found an entirely new element hiding inside the one Berzelius discovered, he was strangely quiet about it. It might be embarrassing to be shown up by your student like that.4
But around Christmastime, the matter was complicated by one of Mosander’s own students, Axel Erdmann. Erdmann claimed to have found a “new earth,” and sent a sample of it to Berzelius. Out of respect for his teacher, Erdmann called the mineral “Mosandrite.”5 6 7
Mosander must’ve felt rather sheepish at that point, but he finally piped up and confessed that well, actually, he had discovered the same thing earlier this year.
This was rather a lot for Berzelius to take in, and he was initially skeptical. But he couldn’t deny the facts, so he congratulated Mosander on the discovery. (Sadly, Erdmann was reduced to a footnote in the history of science.) Berzelius suggested the name “lanthanum,” from the Greek meaning “hidden one.”8
It’s an apt name for the element that leads off this series. The lanthanides are sometimes called the “Rare Earths,” which can be a misleading name to our modern ears. “Rare” in this sense likely meant “newly discovered,” and “earth” was synonymous with “oxide.” (These elements were usually discovered in combination with oxygen as a mineral.)9
In fact, the rare earth elements are impressively common on this planet. Five of them, including lanthanum, are more abundant than lead, and the rest can all be found more commonly than silver or gold.10 The problem is that, due to their chemical similarity to each other, they’re usually found alongside each other and are challenging to isolate.
For instance, lanthanum wasn’t the only element hiding inside that mineral containing cerium. There were five more rare earth elements inside waiting to be discovered. Similarly, within the yttrium-containing mineral yttria, Mosander found terbium and erbium. Later scientists separated ytterbium from erbium, then from erbium sifted out thulium and holmium, then separated dysprosium from holmium. It’s almost like the rare earths were nesting dolls, and each newly separated mineral could be cracked open to find another waiting inside.11 12
The reason the lanthanides were so difficult to separate has to do, like so much of chemistry, with their electron configuration. Remember how the transition metals tuck away each new electron in a way that makes them act similar to each other? The lanthanides are a lot like that, only more so.13
Electrons don’t float around the nucleus all willy-nilly. They encircle the nucleus at very specific distances, in orbits that take a very particular shape. The simplest ones are spheres. Elements in groups 13 through 18 fill shells that look like dumbbells, and the transition metals start filling orbitals shaped like beans that surround the nucleus.
After lanthanum, electrons start occupying orbitals with even more complex shapes. They kind of look like balloons, most of the time.
Here’s what complicates matters: these balloon-shaped orbitals are difficult for other atoms to interact with. It’s almost like these electrons are chemically invisible. So even though we’re adding an electron with each lanthanide, their valency remains constant. With minor exceptions, elements 57 through 71 each have three electrons for other atoms to play with. In some respects, the lanthanides behave even more similarly than lithium, sodium, and potassium do.14 15 16
Many of the stories of discovery that we’ll learn over these fifteen episodes will highlight that similarity and the difficulty scientists had in isolating one element from the others. It’s like if you tried to sort all the grains of sand on a beach according to their size.
And yet, for all their similarities, these are unique elements. We’ve really come to appreciate them as individuals over the last century. Scientists found that each element excels in its own niche applications — often as part of the complex electronics and machinery that power our entire civilization: Wind turbines and MRI machines and car engines and jet fighters and much more. The rare earth metals are sometimes compared to vitamins: We don’t need them in vast quantities, but they’re necessary for our lives.17
As you can imagine, this makes them a valuable resource, and sometimes, a political football.
For instance: In the East China Sea, there’s a string of tiny little islands that are claimed by Japan, Taiwan, and China. So long as all three parties stay away from the islands, everything is fine.
But in September of 2010, a Chinese fishing boat wandered into the waters around the islands. A Japanese Coast Guard patrol ordered the fishing boat to stop for inspection; in response, the Chinese boat rammed into the Coast Guard patrol boat.18
The captain and crew were detained by the Japanese.
When the story made the news, though, the part about the fishing boat smashing up the patrol boat was left out. As was the possibility that the Chinese captain might have been drunk.
So the public perception of this incident was that an overzealous patrol had captured an innocent fisherman, and the Japanese government was refusing to release him.
In response, the Chinese government withheld all exports that were bound for Japan… including a major shipment of rare earth metals.
This was a devastating power move. While the whole world depended on rare earths, China produced 97% of the global supply at the time. Businessmen everywhere realized that China had the power to halt the industry of any nation, for any reason.
The market responded the only way it knows how: with sheer and total panic. The prices of some rare earth metals shot up by two thousand percent, practically overnight.
The Chinese government hasn’t been quite so aggressive since the incident with the fishing boat, but they’re well aware of the power they wield. After President Xi Jinping visited a rare earth processing facility in 2019, a ministry spokesperson made a not-so-cryptic comment: “It is normal that the top leader investigates relevant industrial policies. I hope everyone can interpret it correctly.”
That said, China doesn’t exercise complete control over the industry. In the last decade, several countries have ramped up their production of lanthanides, including Australia, the United States, Russia, and India. If push comes to shove, any of those countries could sprint to catch up without too much fuss.19 20 21 22
Likewise, you should be able to procure a sample of lanthanum for your collection without too much fuss, either. Even if global production shut down overnight, so much lanthanum has been used in manufacturing over the years that element 57 is surely within your grasp.
If you have a Toyota Prius, you might already carting around ten pounds of lanthanum every time you pull out of the driveway. Lanthanum is the “metal” within “nickel-metal hydride” batteries, and they’re pretty common. If an electric car battery is not feasible for you, they’re also available in AA form.23
Lanthanum also makes an appearance in very high-quality optical glass — the kind found in quality cameras. Including lanthanum in the glass mixture allows light to pass through the lens without bending that light too much.24 25
For the discerning collector, life will be a little more difficult. There aren’t really any practical uses for pure lanthanum, so if you want some, you’ll have to distill it yourself. Again, the chemistry to do this is extremely tedious, but if you really want to try, why not make like the greats and start with a mineral sample from Ytterby? Lanthanum is bound to be hiding in there somewhere.
Thanks for listening to The Episodic Table of Elements. Music is by Kai Engel. To see what a properly wide periodic table looks like, visit episodic table dot com slash L a.
Next time, we’ll get serious about cerium.
Until then, this is T. R. Appleton, reminding you to wash your hands, chow down on a protein fudge, take whatever injections are recommended in your sector, and remain indoors.
- In Chemistry, Assembling The Modern Periodic Table. Julianna Poole-Sawyer, January 11, 2019.
- Nature’s Building Blocks: An A-Z Guide To The Elements, p. 275. John Emsley, 2011. Usually I don’t cite this book because it’s on my page of always-cited sources, but I happened to use a digital version of the book rather than my print copy this time.
- Encyclopedia.com, Carl Gustaf Mosander. Last updated March 15, 2020.
- In Your Element, Seekers Of The Lost Lanthanum. Brett F. Thornton and Shawn C. Burdette, 2019.
- Episodes From The History Of The Rare Earth Elements, p. 44. Edited by C. H. Evans, 2012.
- Chemicool, Lanthanum Element Facts / Chemistry. Dr. Doug Stewart, October 17, 2012.
- Rare Earths, p. 32-34. Paul Caro, 1998.
- Elementymology & Elements Multidict, Lanthanum. Peter van der Krogt.
- Encyclopedia.com, Lanthanides. Last updated March 20, 2020.
- PeriodicTable.com, Abundance In Earth’s Crust Of The Elements. Theodore Gray. “Up to date, curated data provided by Mathematica’s ElementData function from Wolfram Research, Inc.”
- Elementymology & Elements Multidict, The Discovery And Naming Of The Rare Earths. Peter van der Krogt.
- Rare Earth Materials: Properties And Applications, p. 3-4. A. R. Jha, 2014.
- Slate, They’re Neither Rare Nor Earths. But They Could Save The Planet. Sam Kean, July 15, 2010. (That title is no longer visible on the page, a consequence of being an older article. It is visible in the URL, or on an archived version.
- LibreTexts Chemistry, Lanthanides: Properties And Reactions. Last updated June 5, 2019.
- Foundations Of Chemistry, Valencies Of The Lanthanides. David A. Johnson and Peter G. Nelson, August 29, 2017. This table in particular was helpful.
- Journal Of The Less Common Metals, On The Valence Changes Of Lanthanide Elements In Compounds And The Enthalpies Of Formation And Stabilities Of Their Dihalides. Y.-C. Kim and J. Oishi, June 1979.
- The Verge, Rare Earth Elements Aren’t The Secret Weapon China Thinks They Are. James Vincent, May 23, 2019.
- Distillations from the Science History Institute, Rare Earths: The Hidden Cost To Their Magic. Episode 242, June 25, 2019.
- The Verge, China Can’t Control The Market In Rare Earth Elements Because They Aren’t All That Rare. James Vincent, April 17, 2018.
- Scientific American, Don’t Panic About Rare Earth Elements. Jeremy Hsu, May 31, 2019.
- Wired, Are Rare Earths The Next Pawn In The US-China Trade War? Klint Finley, June 17, 2019.
- Rare Earth Investing News, Top 10 Countries For Rare Earth Metal Production. Charlotte McLeod, May 23, 2019.
- Green Car Reports, Lithium-Ion vs. Nickel-Metal Hydride: Toyota Still Likes Both For Its Hybrids. Bengt Halvorson, December 6, 2018.
- A History Of The Photographic Lens, p. 77. Rudolf Kingslake, 1989.
- The International Leica Society, Rare Earth Glass Leica Lenses: A Quick And Quirky Overview. Jason Schneider, September 5, 2018.