Atomic number 39

Yttrium

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Shells Orbitals 4d 5s

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39 electrons in 5 shells: 2, 8, 18, 9, 2.

Shells are a teaching model: an electron does not travel on a ring at a fixed distance.

Category: Transition metal
Period: 5
Group: 3
Block: d
Standard atomic weight: 88.906(1) Da
Electron configuration: [Kr] 4d¹ 5s²
Phase at 25 °C: solid
Melting point: 1526 °C
Boiling point: 2930 °C
Density: 4.47 g/cm³
Electronegativity (Pauling): 1.22
Discovered: 1794, Johan Gadolin

Neighbours in the table

Sr Zr

A quarry near Ytterby, in Sweden, gave up the mineral in which Johan Gadolin, a Finnish chemist, found yttrium. The find came in 1794 in the history by CIAAW, the atomic-weights commission of the chemists’ international union (IUPAC), and in 1789 in Jefferson Lab’s account. Gadolin’s yttria, the earth that held the element, also dates to 1794 on Los Alamos’s page. The mineral itself was later renamed gadolinite in his honour.

Gadolin’s earth was not one substance. In 1843 Mosander resolved it into the oxides of three elements, according to Los Alamos. He kept the name yttria for the most basic of them, the most strongly base-forming. The other two became erbia and terbia. Wöhler obtained the metal, still impure, in 1828 by reducing the anhydrous chloride with potassium.

Yttrium is [Kr] 4d¹ 5s²: 39 electrons, 2, 8, 18, 9 and 2 from the innermost shell outward. Each d subshell sits in energy between the s and p orbitals of the next shell up, in Chem1’s account. Yttrium’s two 5s electrons are therefore in place before its single 4d electron. Its oxidation states, bookkeeping charges as if all bonds were ionic, are 3, 2 and 1 on Los Alamos’s page; Jefferson Lab gives +3. The metal has a silvery, metallic lustre.

Where it is found

Yttrium makes up 33 milligrams in each kilogram of the Earth’s crust on PubChem’s element record, and seawater holds 1.3 × 10⁻⁵ milligrams per litre. It turns up widely in rare-earth minerals, Los Alamos reports. Monazite sand carries about 3 per cent and bastnaesite about 0.2 per cent, and both are commercial sources. Apollo rock samples from the Moon showed a relatively high yttrium content.

China supplies most of the world’s yttrium from weathered clay deposits in its southern provinces, chiefly Fujian, Guangdong and Jiangxi, in the US Geological Survey’s account. Burma mines similar clays. World mine output in 2024 came to an estimated 15,000 to 20,000 tonnes of oxide equivalent.

In the United States, Mountain Pass in California mined bastnaesite, whose rare earths are about 0.12 per cent yttrium. Florida heavy-mineral sands yield a concentrate carrying yttrium-rich xenotime. With no fully commercial separation plant in the country, the concentrates went abroad for processing, and 93 per cent of imports from 2020 to 2023 came from China.

Why it matters

Metallic yttrium is not widely used, Jefferson Lab notes, though several of its compounds are. Worldwide, the US Geological Survey reports, the oxide goes mostly into ceramics and phosphors. Its ceramic uses include oxygen sensors in car engines, jet-engine coatings, bearings, seals and nozzles for continuous casting. In zirconia ceramics yttrium oxide acts as a stabiliser; calcium or magnesium oxide can replace it, generally giving lower toughness.

Two garnets named for the element carry it into lasers and radar. Yttrium aluminium garnet provides the laser crystals used in dental and surgical procedures and in industrial cutting and welding. The garnet has a hardness of 8.5, on Los Alamos’s figures, and also serves as a simulated diamond. Yttrium iron garnet filters microwaves and controls high-frequency signals in radar.

As an additive, small amounts of yttrium reduce the grain size of chromium, molybdenum, zirconium and titanium, and strengthen aluminium and magnesium alloys, Los Alamos reports. The metal deoxidises vanadium and other nonferrous metals. In cast iron it has been considered as a nodulising agent, making the graphite form compact nodules instead of flakes, and the resulting iron is more ductile. The oxide also has potential in glass, because it melts at a high temperature and lends glass shock resistance and low expansion.

Properties

Properties of yttrium Standard atomic weights from IUPAC/CIAAW (abridged, 2024); other values from PubChem's periodic table, kelvin converted to °C.
Property	Value	Unit	Source
Atomic number	39
Standard atomic weight	88.906(1) Da	Da	IUPAC/CIAAW 2024
Melting point	1526 °C	°C	Los Alamos: 1526 °C
Boiling point	2930 °C	°C	Los Alamos: 2930 °C
Density	4.47 g/cm³	g/cm³
Electronegativity (Pauling)	1.22
Electron configuration	1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹
Phase at 25 °C	solid

Safety

Solid yttrium metal is stable in air, protected by a film of oxide, and NIOSH, the US National Institute for Occupational Safety and Health, calls it noncombustible in bulk. The powder, dust and turnings are another matter: finely divided yttrium is flammable in air and unstable. Yttrium dust irritates the eyes, and NIOSH names the eyes, respiratory system and liver as the organs it affects. For anyone handling yttrium powder or dust at work, the PubChem Laboratory Chemical Safety Summary for yttrium and the NIOSH Pocket Guide card give the handling guidance.

Questions

Where does the name yttrium come from?

From Ytterby, a village in Sweden whose quarry yielded the mineral gadolinite. Gadolin first called the element ytterbium, after the mineral's old name ytterbite, in the history by CIAAW, IUPAC's atomic-weights commission, on PubChem's record; the name was later cut down to yttrium, and ytterbium went to a different element. The same village gave its name to erbium and terbium as well, Los Alamos adds.

Is yttrium a rare earth element?

Yttrium belongs with the rare-earth elements in the US Geological Survey's classification, and it occurs widely in rare-earth minerals, according to Los Alamos. On the periodic table it sits in group 3 of the d-block, a transition metal just ahead of the point where the f-block is inserted. Scandium, above it in the group, is closer in character to yttrium and to the rare-earth metals than to aluminium or titanium, Los Alamos adds.

Is yttrium radioactive?

Natural yttrium is not: it has a single isotope, yttrium-89, according to Los Alamos, and the Atomic Mass Data Center lists nuclides from yttrium-75 to yttrium-109. Yttrium-90 has a half-life, the time for half a sample to decay, of 64.05 hours in the International Atomic Energy Agency's evaluation, all by beta-minus emission. It forms from strontium-90. Its microspheres help treat liver cancer, and it is used to reduce joint pain, in the isotope table of IUPAC, the chemists' international union.

Why is yttrium used in television screens?

Combined with europium, yttrium makes the red phosphor of colour televisions, in Jefferson Lab's account on PubChem's record. It also went into cathode ray tubes, until recently the main component of television sets, Los Alamos notes. Its phosphor compounds now go into flat-panel displays and lighting, and in phosphors, lasers and electronics yttrium generally has no direct substitute, the US Geological Survey adds.