Rare earth is a name given to a group of chemical elements that, despite their name, are relatively plentiful on earth but are well dispersed and so harder to extract in meaningful quantities. The 17 rare earth elements are scandium (Sc), yttrium (Y), 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) and lutetium (Lu). The elements from lanthanum to lutetium, with atomic numbers 57 to 71, are called lanthanides. Scandium (21) and yttrium (39) sit above lanthanum in the periodic table.