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71Lu174.97

Element 71, a lanthanide

Lutetium

The last and densest of the lanthanides, named after Paris, and now a targeted cancer treatment.

At a glance

Symbol
Lu
Atomic number
71
Average atomic mass
174.97
Group
none; it sits in the lanthanide row below the table
Period
6
Family
lanthanide
Electron configuration
[Xe] 4f¹⁴ 5d¹ 6s²
Electronegativity
1.27
Common ions
Lu³⁺

On the table

Periodic table with Lutetium highlighted123456789101112131415161718123456757-7189-103HHeLiBeBCNOFNeNaMgAlSiPSClArKCaScTiVCrMnFeCoNiCuZnGaGeAsSeBrKrRbSrYZrNbMoTcRuRhPdAgCdInSnSbTeIXeCsBaLaCePrNdPmSmEuGdTbDyHoErTmYbLuHfTaWReOsIrPtAuHgTlPbBiPoAtRnFrRaAcThPaUNpPuAmCmBkCfEsFmMdNoLrRfDbSgBhHsMtDsRgCnNhFlMcLvTsOg

Period 6, in the lanthanide row set below the main table. The other lanthanides are tinted, and every cell opens its own article.

Electrons and bonding

Like the other lanthanides, it gives up three electrons to form the Lu³⁺ ion in most of its compounds.

Properties

State at 25 °C
solid
What it looks like
hard, dense, silvery-white metal
Melting point
1663 °C
Boiling point
3402 °C
Density
9.84 g/cm³

Where it is found

One of the rarest and most expensive rare earths, recovered from monazite and xenotime.

Discovery and name

Georges Urbain in Paris, Carl Auer von Welsbach in Austria and Charles James in the United States each separated it from ytterbia around 1907. Urbain published first and named it after Lutetia, the Roman name for Paris.

What it is used for

Lutetium-177 is attached to molecules that seek out certain prostate and neuroendocrine cancers and destroys them with radiation from inside. Lutetium crystals detect gamma rays in PET scanners, lutetium catalysts help refine oil, and the slow decay of lutetium-176 dates meteorites and ancient rocks.

In compounds

Lu₂O₃lutetium oxideLu₂SiO₅lutetium oxyorthosilicate, PET scanner crystalsLuCl₃lutetium chloride