Lutetium

Lutetium is a part of the lanthanide series of the Periodic Table of the Elements. It is classified as a rare earth metal, and is considered the rarest of lanthanides and one of the rarest elements. It does not have a large amount of commercial uses, though it can be used as a catalyst in certain reactions. However, all elements have some purpose, large or small, and as humanity's technology continues to advance, lutetium could eventually find a more expanded contribution to our society.

Properties
Lutetium's appearance is silvery-white and is relatively stable when exposed to air. Lutetium's phase at room temperature is a solid. It is also very soft and ductile, which means that it can be drawn and stretched out into straight wires. The element is radioactive, and its half-life is around 3x1010 years. Lutetium is the hardest and densest of all lanthanides, as well as the heaviest and rarest. While most lanthanides, the sixth row of the periodic table, are difficult to isolate, lutetium is both rare and difficult to isolate.

Physical Properties
There are several different physical properties of lutetium that include, but are not limited to, the following:
 * Atomic Mass- 174.97 g.mol1
 * Boiling Point- 3395 °C
 * Density- 9.7 g.cm-3 at 20°C
 * Electronegativity- 1.2
 * Ionization Energies- 522.7 kJ.mol -1, 1339 kJ.mol -1
 * Melting Point- 1663 °C

Isolation
Pure lutetium has only been isolated recently, and is one of the most complex and difficult elements to prepare. This can be accomplished by reducing any anhydrous LuCl3 or LuF3 by either an alkali metal or alkaline earth metal. Since lutetium is commercially and readily available, it is not necessary for one to isolate it in a laboratory.

Occurrences
Lutetium can be found in practically any compound that also contains the element of Yttrium. It makes up about 0.003% of the commercial source, monazite. Lu naturally occurs with 175Lu and 176Lu, with percentage compositions of 2.6% and 97.4%, respectively. These are both different isotopes of lutetium, the second being extremely radioactive.

Lutetium is most commonly obtained in an ion exchange process that takes place in monazite sand, a material that is very rich in uncommon and rare earth elements. Monazite sand's chemical formula is ((Ce, La, Th, Nd, Y)PO4).

Lutetium makes up about a rather small amount of the earth's crust, appearing in about 0.8 to 1.7 parts per million. However, while these numbers may be small, this percentage is higher than the elements of Iodine, Silver, and Mercury, making lutetium the most commonly found element of the four.

Lutetium can be mined in several different locations, such as Australia, Brazil, China, India, Sri Lanka, and in select parts of the United States of America. The total reserves in the world that harvest lutetium contain a mass total of around 200,000 tons, and the world production of lutetium, in the form of lutetium oxide, is about 10 tons a year.

History and Uses
The name "Lutetium" comes from the word "Lutetia", which was the name of ancient Paris. The element was discovered by Georges Urbain, a French chemist, when he performed experiments with Ytterbium in 1907. He believed that ytterbium was two different elements, and worked to separate the compound. Once they were divided, he named the two new elements "Neoytterbium", which means new ytterbium, and "Lutecium",  whose name was changed to Lutetium in 1949. Neoytterbium was also eventually changed back to ytterbium.

Around the same time, a German chemist named Karl Auer made the exact same discovery. The two elements that he was able to obtain from ytterbium he named "Cassiopeum" and "Aldebaranium", in honor of the constellation Cassiopeia and the star Aldebaran. In Germany, lutetium is still known as cassiopeum. A third chemist from America, named Charles James, made the same discoveries as well, but announced his discoveries after Urbain and Auer. Some scientific authorities give credit for the discovery of lutetium to all three scientists.

The primary use for lutetium is for its lutetium nuclides, which, when stable, can be used as catalysts in alkylation, cracking, hydrogenation, and polymerization through their pure beta radiation emissions after thermal neutron activation. There are virtually no other known commercial uses for lutetium.

Costs and Handling
Lutetium is the rarest of all earth metals. Even though scientists have developed ways to separate different rare-earth elements, such as with ion exchanges (wherein two electrolytes exchange ions with each other), its most current pricing is at $75 per gram. It should also be handled with extreme care, although thought to have a low toxicity rating like other rare-earth metals. There is a greater risk of toxicity through ingestion, but the insoluble salts contained within lutetium are not toxic. Metal dust from lutetium is an explosive and fire hazard, but does not pose any health threats to humans or animals.

Additional Information

 * Lutetium Answer.com. 2010.
 * Lutetium Wikipedia, the free encyclopedia. November 14th, 2010.
 * Element:Lutetium Radiochemistry.org. 2003.