|Atomic mass||173.04 amu|
Ytterbium is the first rare-earth to be discovered. Discovered in 1878, its name is easily confused with the name of another rare-earth element, yttrium.
Ytterbium is a very soft, silvery-white metal. It is easily oxidized. An oxide layer forms on freshly cut surface because the metal reacts with air. This element is part of the lanthanide series of transition elements. Most commercial-grade ytterbium is obtained from monazite sand, which is a mixture of phosphates of calcium, cerium and most of the other rare-earths.
Ytterbium is separated from other impurities by an ion exchange process.
The most important use of ytterbium is as a doping agent for garnet crystals in lasers. It has been used to improve the mechanical properties of steel. Ytterbium has several radioactive isotopes, one of which is used in radiography of metal parts and in medical diagnostic work.