lanthanide series

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lanthanide series (lanthanide elements, rare-earth metals) Series of 15 rare metallic elements with atomic numbers from 57 to 71. They are, in order of increasing atomic numbers: lanthanum (sometimes not considered a member), cerium, praseodymium, neodymium, promethium (the only radioactive member), samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Their properties are similar. The shiny metals occur in monazite and other rare minerals and are placed in group III of the periodic table. Each element is analogous to the corresponding radioactive actinide series.

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