40 Fun Facts About Lanthanides

Terbium, erbium and ytterbium are all named after Ytterby, a quarry village in which country?

Sweden's Ytterby holds a naming record: yttrium is called after the same village, so one small place appears four times on the periodic table.

Neodymium is alloyed with iron and boron to make the strongest commercial type of which component in headphones?

Magnets made of neodymium, iron and boron were developed independently in 1984 by General Motors and Sumitomo, and now sit inside hard drives and cordless tools too.

Europium transformed colour television in the 1960s by supplying an efficient, vivid phosphor for which colour?

Red europium phosphors lit up cathode-ray screens from the 1960s. The same glow appears on euro banknotes under ultraviolet light, as a check against forgery.

Promethium is named after Prometheus, the Titan of Greek mythology who stole what from Mount Olympus?

Fire was a pointed choice for an element born in a nuclear reactor: the name was meant to symbolise both the daring and the possible misuse of human intellect.

Ferrocerium, a cerium alloy that showers sparks when scraped, is the so-called flint in which everyday objects?

Lighters use a man-made 'flint' that works backwards: real flint is a rock that strikes sparks off steel, while ferrocerium is itself scraped away by a hardened steel wheel.

Gadolinium compounds are injected into patients to sharpen the images from which kind of hospital examination?

MRI scan contrast agents built around gadolinium spread through the body after injection, but they do not readily cross an intact blood–brain barrier.

Which country has supplied most of the world's lanthanides since undercutting rival mines' prices in the 1990s?

China supplied around 90% of global demand in 2019, after its low prices in the 1990s forced many mines in other countries to close.

Lutetium, the final lanthanide, takes its name from Lutetia, the Roman-era name for which European capital?

Paris won a naming fight: French chemist Georges Urbain chose the name, while an Austrian rival who found the element independently wanted to call it cassiopeium.

Surgeons use the beam of a holmium laser to break up which painful deposits inside the body?

Kidney stones are a routine target for holmium laser surgery, which is valued for its precision and for doing minimal damage to the tissue around the stone.

Lanthanum goes by the kilogram into the nickel–metal hydride battery packs of which fuel-saving vehicles?

Hybrid cars are rolling lanthanum stores: the battery of a 2008 Toyota Prius needs 10 to 15 kilograms of the metal.

The lanthanides, scandium and yttrium are known together by which collective name, widely called a misnomer?

Rare earths are not actually scarce: the label stuck because they are found only in compounds, never as pure metals, and are difficult to isolate and purify.

To stop the periodic table becoming impractically wide, the lanthanides are customarily printed in which position?

Below the main body is purely a formatting convention: a rarely used wide version of the table slots the lanthanides into their true place in its sixth row.

Which series, home to uranium and plutonium, sits directly beneath the lanthanides on a standard periodic table?

Actinides differ from the row above in one striking way: every lanthanide except promethium occurs in nature in appreciable quantities, while most of the lower row barely occurs at all.

Cerium, the most abundant lanthanide, is about as plentiful in Earth's crust as which familiar metal?

Copper and cerium each make up roughly 68 parts per million of the crust, which leaves cerium more abundant than everyday metals such as lead and tin.

Even lutetium, one of the scarcest lanthanides, is more common in Earth's crust than which of these metals?

Silver is the scarcer of the two in the crust, yet lutetium was far slower to reach the laboratory shelf: the pure metal was first produced only in 1953.

Erbium-doped amplifiers boost the signals travelling long distances through which kind of cable?

Fibre-optic lines lose the least light at a wavelength of about 1,550 nanometres, and erbium ions happen to amplify light in just that region.

Lanthanum oxide is a prized ingredient in which components of high-end cameras and telescopes?

Lenses made with lanthanum glass bend light strongly while splitting it into colours very little, a pairing of high refractive index and low dispersion.

The word lanthanide comes from the Greek lanthanein, a verb with which meaning?

To lie hidden first described lanthanum, found lurking as an impurity inside a cerium compound; the whole series later took its name from that one element.

Dysprosium's discoverer needed more than 30 attempts to isolate it, then gave it a Greek name with which meaning?

Hard to get stayed true for decades: dysprosium was identified in 1886 but not isolated in pure form until ion-exchange techniques arrived in the 1950s.

Praseodymium's name describes the green colour of its salts by comparing them to which vegetable?

Leek green is the first half of the name; the second half, Greek for twin, was inherited from didymium, the supposed element it was split from.

Didymium filters, which cut out the yellow glare of hot sodium, protect the eyes of which craftspeople?

Glassblowers work in a flame turned yellow by sodium in the hot glass; didymium removes that one colour without harming general vision, unlike dark welding goggles.

Carl Auer von Welsbach, who split didymium into praseodymium and neodymium, also invented which lighting device?

Gas mantle fabric, loaded with thorium and cerium oxides, glows bright white when heated by a flame; it brought light to the streets of Europe in the late 19th century.

Promethium, the only lanthanide with no stable isotopes, was first produced in 1945 at which American laboratory?

Oak Ridge chemists found it among the fission products of uranium reactor fuel, but they were too busy with military research to announce the discovery until 1947.

Nearly all lanthanides fall in which section of the periodic table, named after the electron orbital being filled?

f-block membership has one exception in the series: lutetium is usually classed as a d-block element, yet it behaves so much like the other fourteen that it is counted with them.

Running from lanthanum to lutetium, the lanthanide series covers which span of atomic numbers?

57 to 71 takes in fifteen metals whose outermost electron shell has the same configuration in every case, which is why they behave so much alike.

Because 4f electrons shield the nucleus poorly, what happens to lanthanide ions as atomic number rises?

They get smaller, an effect called the lanthanide contraction. It leaves hafnium so close in size to zirconium that hafnium went undiscovered until 1923, 134 years after its twin.

Ytterbium atoms, laser-cooled and trapped in a lattice of light, set a 2013 stability record for which instruments?

Atomic clocks built on about 10,000 ytterbium atoms at NIST would stay accurate to within a second over a period comparable to the age of the universe.

Gadolinium is used in nuclear reactor shielding because it is exceptionally good at absorbing which particles?

Neutrons are captured by gadolinium-157 more readily than by any other stable nuclide; only xenon-135 does better, and it is radioactive.

Mountain Pass, the mine that made the United States the leading lanthanide producer for decades, is in which state?

California's deposit was found by accident: prospectors searching for uranium in 1949 noticed unusually high radioactivity, and it turned out to mark a different prize.

Gadolinium honours Johan Gadolin, first to analyse the mineral gadolinite, a chemist from which present-day country?

Finland regards Gadolin as the founder of its chemistry research. The 'new earth' he identified in that mineral was the first compound of the whole family ever found.

Samarium takes its name from the mineral samarskite, making it the first element named, indirectly, after what?

A person, and not a famous scientist: Vassili Samarsky-Bykhovets was a Russian mine official whose name had already been given to the mineral.

Erbium oxide is used as a colourant to give glass, cubic zirconia and porcelain which delicate colour?

Pink erbium glass often ends up in sunglasses and jewellery, and it is also chosen where infrared light needs to be absorbed.

Neodymium is built into the generators of some of which towering renewable-energy machines?

Wind turbines with neodymium permanent magnets can be built direct-drive: the rotor turns the generator itself, with no gearbox in between.

Small amounts of lanthanum are added to many swimming-pool products in order to starve which unwanted growth?

Algae feed on phosphates, which lanthanum removes from the water; lanthanum-treated clay is spread on lakes for the same reason.

Cerium was named after Ceres, discovered two years earlier and regarded at the time as which kind of object?

A planet was the first verdict on Ceres, which was later demoted to an asteroid; it takes its own name from the Roman goddess of agriculture and grain crops.

Which English physicist measured the atomic numbers of the known elements and found in 1914 that number 61 was missing?

Henry Moseley confirmed a gap that the chemist Bohuslav Brauner had suggested in 1902; the missing lanthanide, promethium, was not produced for another three decades.

Carl Axel Arrhenius, who in 1787 found the heavy dark mineral that began the lanthanide story, had which profession?

Army officer Arrhenius was an artillery lieutenant and amateur geologist who picked up the rock while visiting the feldspar mine at Ytterby; it is now called gadolinite.

Thulium irradiated in a nuclear reactor becomes the radiation source in portable versions of which devices?

X-ray units built around thulium-170 have a useful life of about one year, serving medical and dental diagnosis and the hunt for defects in inaccessible components.

Lecoq de Boisbaudran, discoverer of samarium and dysprosium, had earlier found which element and named it after France?

Gallium comes from Gallia, the Latin for Gaul. It was later suggested that he had really named it after himself, since gallus is the Latin translation of the French le coq.

IUPAC prefers the name lanthanoid because its rival's suffix, -ide, is normally reserved in chemistry for which things?

Negative ions get the -ide ending, while -oid signals similarity to a member of a family of elements; even so, the older name is still commonly used.