A lanthanide is any of the 15 metallic chemical elements with atomic numbers 57–71, from lanthanum through lutetium. In the periodic table, the first fourteen fill the 4f orbitals. Lutetium is also often considered a lanthanide, despite being a d-block element and a transition metal. The IUPAC lists the 15 elements La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, under the collective name lanthanoid, which it recommends as chemically more correct for this series.