An Overview about the Chemical Element Lutetium


Symbol: Lu

Atomic Number: 71

Atomic Mass: 174.967 amu (atomic mass units)

Melting Point: 1663 C (1936 K, 3025 F)

Boiling Point: 3402 C (3675 K, 6156 F)

Number of Protons: 71

Number of Electrons: 71

Number of Neutrons: 104

Classification: Rare Earth Metal

Group Name: Lanthanide or Lanthanoid

Crystal Structure: Hexagonal

Density @ 293 K: 9.84 grams per cubic centimeter

Color: silver

The history of the discovery of the element lutetium is one of confusion. It starts in 1843 when the Swedish chemist Carl Gustaf Mosander separated the mineral gadolinite into three substances yttria, erbia and terbia. Owing to the similarities in their names terbia was renamed erbia and erbia became terbia. The rare earth elements terbium and erbium were found in the renamed terbia and erbia.

In 1878 Jean Charles Galissard de Marignac found that erbia consisted of two substances one was left with the name erbia as it consisted of erbium oxide the other he called ytterbia believing it to contain the element ytterbium. The chemists examining the new element found inconsistent results and in 1907 the French chemist Georges Urbain proved that ytterbia actually contained two elements. He called these two elements neoytterbium and lutecium.

At about the same time Urbain found his new elements the German chemist Carl Auer von Welsbach also found to new elements that he called albebaranium and cassiopium. These elements were chemically identical to neoytterbium and lutecium. Eventually Urbain was credited with the discovery and was given the right to name the new elements. Chemists later changed neoytterbium back to ytterbium and the spelling of lutecium to lutetium.

The name lutetium came from “Lutetia” which is the ancient name of the city of Paris.

The oxidation state of lutetium is +3 and its ionization energy is 5.426 eV. The silver/white element is fairly stable in air.

Lutetium has two naturally occurring isotopes. The most common is lutetium-175 which makes up 97.41% of the total and is stable. The remaining 2.59% is made up of the unstable isotope lutetium-176 which is a beta emitter with a half life of 40,000,000,000 years. Other unstable isotopes of lutetium with mass numbers ranging from 150 to 184 are known.

Lutetium is one of the rarest of the naturally occurring rare earth metals. It has a crustal abundance of only 0.8 milligrams per kilogram. To separate and prepare a pure sample of the metal is still very difficult. It can be purified by the reduction of anhydrous lutecium chloride (LuCl3) or lutetium fluoride (LuF3) with an alkali or alkaline earth metal.

Very few industrial processes employ lutetium. Some of its radioactive isotopes can be used to catalyze petroleum cracking. They can also be used as catalysts in hydrogenation and polymerization processes.