ingredient information
Lutetium is a chemical element with the symbol Lu and atomic number 71. A silvery-white rare metal, lutetium has the smallest atomic radius and is the heaviest and hardest member of the rare-earth group. One of its radioactive isotopes (176Lu) is used in nuclear technology to determine the age of meteorites. Lutetium usually occurs in association with yttrium and is sometimes used in metal alloys and as a catalyst in various chemical reactions. A strict correlation between periodic table blocks and chemical series for neutral atoms would describe lutetium as a transition metal because it is in the d-block, but it is a lanthanide according to IUPAC. Lutetium is one of the rarest and is the most expensive rare-earth element.