40 Fun Facts About Lanthanum

Lanthanum's name comes from an ancient Greek word with which meaning?

To lie hidden fits: lanthanum sat unnoticed for decades inside a mineral that chemists believed held only one new element.

The 2008 model of which hybrid car carried 10 to 15 kilograms of lanthanum in its rechargeable battery pack?

Toyota Prius batteries store their charge in a lanthanum-rich alloy, usually a cheap blend with other rare earths in place of the pure metal.

RaLa, short for radioactive lanthanum, was a series of implosion tests begun during which secret wartime program?

Manhattan Project scientists used the blasts to perfect the implosion that squeezes a plutonium bomb's core; a history of the work called RaLa the most important single experiment for the final design.

The parent isotope that steadily produced radioactive lanthanum for RaLa tests was nicknamed after which farm animal?

A cow was the nickname because fresh radioactive lanthanum could be 'milked' from it again and again as the parent isotope decayed.

Mischmetal, an alloy that is roughly a quarter lanthanum, is best known as a key ingredient of which pocket item?

Cigarette lighters strike their sparks from a 'flint' that is really mischmetal hardened with iron and magnesium oxides.

Lanthanum carbonate, a phosphate-binding medicine for people, has also been sold by Bayer Animal Health for which pets?

Cats can suffer the same build-up of phosphate in the blood as people, and the feline version went by the trade name Renalzin.

Although it is called a rare earth, lanthanum is almost three times as abundant in Earth's crust as which metal?

Lead is the scarcer one; rare earths got their label because few deposits were known at first and mining them is slow and costly.

Lanthanum gives carbon arc lamps a sunlight-like glow, which once made the element a staple of which industry?

Movies were once shot and projected by carbon arc light, a job that swallowed about a quarter of all rare-earth compounds produced.

Lanthanum carbonate, sold as Fosrenol, treats high blood phosphate in patients with chronic disease of which organs?

Kidneys that are failing cannot clear phosphate, so the drug traps it in food; the tablets are so large that they are meant to be chewed.

Small amounts of lanthanum in many swimming pool products strip out the phosphates that feed which unwanted growth?

Algae starve without phosphate, and the same trick is used on whole lakes, where a lanthanum-laced clay locks the nutrient into an inert mineral.

Lanthanum oxide gives glass a high refractive index and low dispersion, which makes it prized for making what?

Camera lenses and telescope lenses both rely on lanthanum glass, and the oxide also helps the glass resist attack by alkalis.

Early gas mantles made with lanthanum oxide in the 1880s sold poorly and gave off light with which tint?

Green-tinted light did the mantles no favors, and the company that Auer von Welsbach founded to make them failed in 1889.

Lanthanum's oxide coating does not shield the metal beneath but flakes off like which familiar product of corrosion?

Rust is the usual comparison: a centimeter-sized lump of lanthanum left in air corrodes away completely within a year.

Lanthanum 'sponge' alloys can reversibly soak up as much as 400 times their own volume of which gas?

Hydrogen goes in and out on demand, and the alloy gives off heat every time it fills, which interests designers of energy-saving systems.

Lanthanum was discovered in a heavy mineral dug from the Bastnäs mine, which is in which Nordic country?

Sweden's Bastnäs mine had been puzzling chemists since 1751, when a mineralogist first noticed the unusually heavy stone there.

Bayan Obo, a massive deposit of the lanthanum ore bastnäsite and the largest rare-earth find yet, is in which country?

China's Bayan Obo mines, in Inner Mongolia, were turning out 45% of the world's rare earths by 2005.

Mischmetal, a rare-earth alloy rich in lanthanum, takes its name from which language's words for mixed metal?

German gave it the name Mischmetall; its inventor devised the alloy while hunting for uses for the rare earths left over from making gas mantles.

Adding a little lanthanum makes which common alloy more malleable, more ductile and better at resisting impact?

Steel toughens with tiny doses, while lanthanum added to molybdenum does a different job, making that metal less hard.

Lanthanum compounds go into the cracking catalysts that oil refineries use to turn heavy crude into which product?

Gasoline is the prize: by 2006 some 400 refineries ran these cracking units, which handle about a third of the crude oil those plants refine.

Cathodes made of lanthanum hexaboride feed electrons to Hall-effect thrusters, a kind of ion engine that propels what?

Spacecraft are not the only users: the same hot crystals supply the beam in electron microscopes, where they outlast and outshine tungsten.

A lanthanum-based ceramic discovered in 1986 won a Nobel Prize as the first high-temperature example of which material?

Superconductor is the word: the black lanthanum-copper oxide carried current with no resistance at a then unheard-of temperature, and its finders shared the 1987 physics Nobel.

Lanthanum has no known role in the human body, but which organisms from hot volcanic mud use it to grow?

Bacteria found in volcanic pools near Naples use lanthanum in an enzyme that helps them feed on methane gas, though a few sister elements can stand in for it.

Lanthanum was first detected in the 1830s as an impurity in a nitrate of which more abundant rare-earth metal?

Cerium nitrate was roasted in air and then treated with dilute nitric acid, a simple routine that teased out the oxide of a new element.

Which alkaline earth metal, element 56, sits immediately before lanthanum in the periodic table?

Barium is also lanthanum's parent in a sense: radioactive barium-140 decays into lanthanum-140, the isotope used in wartime implosion tests.

Lanthanum oxide is added to tungsten welding electrodes as a safer substitute for which radioactive element?

Thorium gives welders excellent arcs that start easily, but its dust and vapors are a health risk, hence the switch.

Which chemist found lanthanum in the 1830s but hesitated to announce it for fear of embarrassing his mentor?

Carl Gustaf Mosander trained as a pharmacist and physician, and his find showed that an 'element' his own teacher had discovered was really a mixture.

In chemical reactions, lanthanum usually gives up three electrons to reach the stable configuration of which noble gas?

Xenon has 54 electrons, three fewer than lanthanum, so shedding three leaves the colorless La3+ ion found in nearly all of its compounds.

Lanthanum oxide reacts with water so eagerly that it gives off plenty of heat along with what else?

A hissing sound comes off as the white powder turns into lanthanum hydroxide, which then goes on to soak up carbon dioxide from the air.

Lanthanum hexaboride, a ceramic almost as hard as diamond that is used in hot cathodes, is which striking color?

Purple-violet crystals of the compound rate 9.5 on the Mohs hardness scale and melt only at 2,210 °C.

Lanthanum is an essential ingredient of ZBLAN, a heavy glass whose optical fibers excel at carrying which radiation?

Infrared light passes through ZBLAN unusually well, and a 1998 study showed that making the glass in zero gravity leaves fewer flaw-causing crystals.

Didymium, a supposed element found with lanthanum, was named from the Greek for what because the two were so alike?

Twin was a fitting name, yet didymium was no element at all: in 1885 it was split into two new metals.

Lanthanum's name was suggested by which eminent chemist, the mentor and housemate of the element's discoverer?

Jöns Jacob Berzelius had retired in 1832 so that this same student could succeed him as professor of chemistry and pharmacy.

Chemists have long argued over whether lanthanum or which other element belongs below yttrium in group 3?

Lutetium was the choice of a 2021 report by chemistry's naming body, which suggested placing it under yttrium as a compromise.

A crystal of a lanthanum compound is the sensing element in a common electrode for measuring which ion in water?

Fluoride ions hop between gaps in the crystal, which is doped with a little europium to create them, so the electrode responds to almost nothing else.

Bastnäsite and which other mineral, often gathered from heavy beach sands, supply most of the world's lanthanum?

Monazite is a phosphate that usually holds every rare earth at once, which makes pulling lanthanum out of it a longer job than from bastnäsite.

The chemist who discovered lanthanum went on to find terbium and which other element named after Ytterby?

Erbium and terbium were both teased out of yttria in 1843, though the two names were later swapped in the confusion that followed.

Rare, radioactive lanthanum-138 is thought to form when which nearly massless particles strike stable nuclei?

Neutrinos get the credit because the usual star-forging routes of neutron capture cannot make this isotope, whose half-life is about 100 billion years.

Lanthanum strontium manganite is the cathode of choice in commercial solid oxide versions of which power source?

Fuel cells of this type run very hot, and the material earns its place because it barely reacts with their zirconia electrolyte, which extends their life.

Phoslock, a lanthanum-laced clay that cleans up polluted lakes, was developed by the science agency of which country?

Australia's CSIRO developed the clay in the late 1990s, and its first large trial came in January 2000 on the Canning River.

Which radioactive element is lanthanum's heavier counterpart and likewise gives its name to a whole series?

Actinium mirrors lanthanum in an odd way too: as lone atoms, neither has any electrons in the f shell that defines its series.