lutetium

Lutetium

Name:Lutetium

Symbol:Lu

Atomic Number:71

Atomic Mass:174.967

Density: 17.78 g/cm^3

Melting Point:1652 �C

Boiling Point:3402 �C

Group Number:3

Group Name:(none)

Standard State:Solid at room temperature

Color:silvery white

Classification:Metallic

Pure metal lutetium has been isolated only in recent years and is one

of the more difficult to prepare. It can be prepared by the reduction

of anhydrous LuCl[3] or LuF[3] by an alkali or alkaline earth metal.

The metal is silvery white and relatively stable in air. It is a rare

earth metal and perhaps the most expensive of all rare elements. It is

found in small amounts with all rare earth metals, and is very

difficult to separate from other rare elements.

Isolation

Lutetium metal is available commercially so it is not normally

necessary to make it in the laboratory, which is just as well as it is

difficult to isolate as the pure metal. This is largely because of the

way it is found in nature. The lanthanide are found in nature in a

number of minerals. The most important are xenotime, monazite, and

bastnaesite. The first two are orthophosphate minerals LnPO[4] (Ln

denotes a mixture of all the lanthanide except promethium which is

vanishingly rare) and the third is a fluoride carbonate LnCO[3]F.

Lanthanides with even atomic numbers are more common. The most common

lanthanide in these minerals are, in order, cerium, lanthanum,

neodymium, and praseodymium. Monazite also contains thorium and

yttrium which makes handling difficult since thorium and its

decomposition products are radioactive.

For many purposes it is not particularly necessary to separate the

metals, but if separation into individual metals is required, the

process is complex. Initially, the metals are extracted as salts from

the ores by extraction with sulphuric acid (H[2]SO[4]), hydrochloric

acid (HCl), and sodium hydroxide (NaOH). Modern purification

techniques for these lanthanide salt mixtures are ingenious and

involve selective complexation techniques, solvent extractions, and

ion exchange chromatography.

Pure lutetium is available through the reduction of LuF[3] with

calcium metal.

2LuF[3] + 3Ca -> 2Lu + 3CaF[2]

This would work for the other calcium halides as well but the product

CaF[2] is easier to handle under the reaction conditions (heat to 50�C