Wednesday, February 10, 2010


There are 118 elements on the periodic table. Many are well-known - everyone knows to iron, copper, tin, and oxygen. Others are somewhat more obscure, but most folks have still heard of barium, tungsten, or thallium. However, there are a few truly obscure ones. For example, no one knows lutetium.

Perhaps that's because it's not used for... well, much of anything, really. Or that it's ridiculously rare. And it's almost impossible to isolate. That doesn't mean, though, that it's not still pretty cool and worthy of attention.

Lutetium is element #71, with 71 protons, and has 104 neutrons in its single stable isotope, 175Lu, which makes up 97.41% of all naturally made lutetium. However, the isotope 176Lu, with 105 neutrons, has a half-life of 37.8 billion years, makes up 2.59% of natural lutetium. There are also 32 other radioisotopes of lutetium, with atomic masses ranging from 150 (79 neutrons) to 184 (113 neutrons) and half-lives from 150 nanoseconds to 3.31 years, or 37.8 billion years in the case of 176Lu.

Lutetium was discovered in 1907 by Georges Urbain; it was one of the last of the non-radioactive elements to be discovered. He as the discoverer suggested 'lutecium' (from the Latin Lutetia meaning Paris [the city of light]) which was changed to lutetium for standardization in 1949.

Coming tomorrow: lutetium uses!

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