Lanthanum: the story on HearLore

Lanthanum

In 1839, a Swedish chemist named Carl Gustaf Mosander was attempting to purify cerium nitrate when he stumbled upon a substance that refused to be separated from its parent compound. He named this new element lanthanum, derived from the ancient Greek word lanthanein, meaning to lie hidden, because it had been lurking within the cerium sample all along. Mosander, who lived in the same house as the famous chemist Jöns Jacob Berzelius, had spent years trying to isolate pure lanthanum, but the element's chemical properties were so similar to cerium that it remained elusive for decades. It was not until 1923 that pure lanthanum metal was finally isolated, nearly a century after its initial discovery. The name itself tells a story of scientific frustration and persistence, as lanthanum was the first element to be identified as part of what would become known as the lanthanide series, yet it was the last to be fully understood and separated. Mosander's discovery was not just a chemical breakthrough; it was a revelation that the periodic table was far more complex than anyone had imagined, with elements hiding in plain sight, waiting for the right techniques to be revealed.

A Soft Metal With A Loud History

Lanthanum is a soft, silvery-white metal that tarnishes slowly when exposed to air, turning completely dark after several hours and readily burning to form lanthanum oxide. Despite being classified as a rare-earth element, lanthanum is actually the 28th most abundant element in the Earth's crust, almost three times as abundant as lead. It is found in minerals such as monazite and bastnäsite, where it composes about a quarter of the lanthanide content. The process to extract pure lanthanum is so complex and time-consuming that it was not achieved until 1923, long after its discovery. The metal has a relatively high resistivity of 615 nΩm at room temperature, which is significantly higher than that of good conductors like aluminum. Lanthanum is the least volatile of the lanthanides and has a hexagonal crystal structure at room temperature, which changes to a face-centered cubic structure at 310°C and a body-centered cubic structure at 865°C. Its chemical reactivity is high, and it reacts with halogens at room temperature to form trihalides, and upon warming, it forms binary compounds with nonmetals such as nitrogen, carbon, sulfur, phosphorus, boron, selenium, silicon, and arsenic. The element's large atomic radius makes it the most reactive among the lanthanides, and it corrodes completely in a year as its oxide spalls off like iron rust, instead of forming a protective oxide coating like aluminum, scandium, yttrium, and lutetium.

The Science Of Hidden Electrons

When was lanthanum discovered by Carl Gustaf Mosander?

Carl Gustaf Mosander discovered lanthanum in 1839 while attempting to purify cerium nitrate. He named the element lanthanum from the Greek word lanthanein meaning to lie hidden because it had been lurking within the cerium sample all along.

When was pure lanthanum metal first isolated after its discovery?

Pure lanthanum metal was first isolated in 1923 nearly a century after its initial discovery in 1839. The element remained elusive for decades because its chemical properties were so similar to cerium that it could not be separated easily.

How abundant is lanthanum in the Earth's crust compared to other elements?

Lanthanum is the 28th most abundant element in the Earth's crust and is almost three times as abundant as lead. It is found in minerals such as monazite and bastnäsite where it composes about a quarter of the lanthanide content.

What are the primary modern uses of lanthanum in batteries and alloys?

Lanthanum is used as an anodic material in nickel-metal hydride batteries and in hydrogen sponge alloys capable of storing up to 400 times their own volume of hydrogen gas. Mischmetal containing 25% to 45% lanthanum is used in lighter flints and as an anodic material in batteries.

Does lanthanum have a known biological role in humans or bacteria?

Lanthanum has no known biological role in humans but is used by some bacteria as a cofactor for the methanol dehydrogenase of the methanotrophic bacterium Methylacidiphilum fumariolicum SolV. It is used as a phosphate binder in cases of end stage renal disease and as an electron-dense tracer in molecular biology.

What was the price of lanthanum oxide in 2011 and 2012 according to IREESM?

The price of lanthanum oxide rose steeply to $140,000 in mid-2011 and fell back to $38,000 by early 2012. The Institute of Rare Earths Elements and Strategic Metals reported these figures for a metric ton of 99% lanthanum oxide FOB China.

Lanthanum

A Soft Metal With A Loud History

The Science Of Hidden Electrons

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