Lanthanides and Actinide Series are two series of elements in the periodic table. According to IUPAC, lanthanide series consists of 15 elements and their atomic numbers range from 57 to 71. The series start from lanthanum and ends on lutetium. These are all f-block elements except for lutetium, which is d-block. Another series in the periodic tables is actinide series, which comprises of 15 elements and their atomic numbers lie between 89 to 103. The name of the series is given because of the name of the first element of the series, actinium which means, "radioactive".