By Jonny Lupsha, Wondrium Staff Writer
Rare earth elements have changed modern technology all around us. The 17 rare earth elements made X-rays safer and are used to make electric vehicle batteries. General Motors will source them for use in electric cars.
General Motors (GM) has announced that it will resurrect its long-dead campaign to utilize rare earth magnets. This time, they’ll turn to the group of elements to help power their electric cars. The news follows an October announcement that the automaker will invest in a battery cell development center in Michigan to lower the cost of manufacturing electric vehicles.
Before that, GM announced earlier this year that it will cease production of gas-powered vehicles by 2036.
Surprisingly, rare earth elements are rather abundant. In his video series Understanding the Periodic Table, Dr. Ron B. Davis, Jr., Associate Teaching Professor of Chemistry at Georgetown University, explains what they are and why they’re in that little standalone pair of rows on the periodic table.
The Landing Strip
According to Dr. Davis, the rare earth elements have become implemented everywhere in modern life from headphones to wind farms. Despite their name, which comes from the fact that they’re rare than many common elements, they’re easily found.
“Cerium, which most people, even today, have never heard of, is more abundant than copper,” he said. “The top three most abundant members of the group are more common than tin or lead. And the entire group, with one radioactive exception, is more abundant than silver—and far more abundant than gold.”
With regard to auto manufacturers specifically, hybrid and electric vehicles contain large batteries that are often made of “nickel-metal hydride.” The “metal” in that battery is mostly lanthanum, one of the rare earth elements. Each battery that uses lanthanum uses over 20 pounds of it, and those batteries are smaller and lighter than older lead-acid batteries.
“To understand how elements so rarely talked about can be so useful, we travel to the f-block of the periodic table, that long ‘landing strip’ of elements that’s strangely detached from the remainder of the table,” Dr. Davis said. “The first thing to remember is that f-block elements don’t really belong in that location. In reality, the partially-filled f-subshells actually belong between the s-block and the d-block.”
In Plain(er) English…
In other words, groups of electrons orbit the nucleus of an atom in different ranges from the nucleus, just like the planets around the Sun, if there were multiple planets on each orbit. These orbits are called electron shells. Each shell can only hold a certain number of electrons. Each shell is also composed of subshells. An f-subshell can hold 14 electrons.
Back to Dr. Davis’s point, the periodic table is grouped by elements with certain orbital characteristics. All the rare earth elements in the top row at the bottom of the periodic table could go up with the rest of the elements, starting just to the right of barium—but there’s one problem, and it explains automakers’ search for rare earth elements.
“The f-shell has 14 electrons—it’s an even number, just like the other shells: 2, 6, 10, and 14,” Dr. Davis said. “In yet another curious violation of the Aufbau principle—”which states that an electron occupies orbitals in order from lowest energy to highest—”lanthanum and actinium do not place their outermost electron in an f-orbital, but in a d-orbital.”
Due to this strange electron sorting, lanthanum would be classified as a different kind of metal than other elements in the f-block and would technically split the d-block in half.
“Chemically, all these [rare earth] elements are very similar,” Dr. Davis said. “Magnetically, the huge size of the f-shell allows for an unprecedented range of optical and electromagnetic properties, thanks to the fact that magnetism, at its core, is driven by the presence of unpaired electrons.”
GM is pinning a lot of its company’s future on those unpaired electrons.