Lutetium is a chemical element with the symbol Lu and atomic number 71. It is a silvery-white metal, which resists corrosion in dry air, but not in moist air. Lutetium is the last element in the lanthanide series, and it is traditionally counted among rare-earth. Lutetium is generally considered the first element of the 6th-period transition metals by those who study the matter, although there has been some dispute on this point.

Lanthanide Chemical Elements

The lanthanide or lanthanoid series of chemical elements comprises the fifteen metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium.

These fifteen lanthanide elements [Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (Lu)], along with the chemically similar elements scandium and yttrium, are often collectively known as the rare earth elements.