Dysprosium Group Series

Rare earth elements are a series of chemical elements of the periodic table, including the elements with atomic numbers 57 through 71, and, named in order, are 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). Yttrium (Y, atomic no. 39) and scandium (Sc, atomic no. 21) are sometimes included in the group of rare earth elements. The elements cerium (Ce, atomic no. 58) through lutetium (Lu, atomic number 71) are commonly known as the lanthanide series. As will be clearer later, there are ample reasons to include Y as a rare earth, but the inclusion of Sc is less common and more controversial. 

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