lanthanide series


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Related to lanthanide series: actinide series, Transition metals

lanthanide series

lanthanide series, a series of metallic elements, included in the rare-earth metals, in Group 3 of the periodic table. Members of the series are often called lanthanides, although lanthanum (atomic number 57) is not always considered a member of the series. The series always includes the 14 elements with atomic numbers 58 through 71, which are (in order of increasing atomic number) cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. All of the members of the series very closely resemble lanthanum and one another in their chemical and physical properties; as the atomic number increases in this series, added electrons enter the 4f electron orbital. Chemically, they are about as reactive as calcium. They all form trivalent compounds; some also form divalent or tetravalent compounds. The lanthanides have similiar sizes so that any given compound of the rare earths is likely to crystallize with the same structure as any other rare earth; however, the lattice parameters become smaller and the crystal denser as compounds proceed across the series.
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lanthanide series

[′lan·thə‚nīd ‚sir·ēz]
(chemistry)
Rare-earth elements of atomic numbers 57 through 71; their chemical properties are similar to those of lanthanum, atomic number 57.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The structural phase transition temperatures, oxygen stoichiometry and characteristics of the [T.sub.c] plateaus appear to follow a trend anticipated from the dependence of the ionic radius on the number of f electrons as R progresses across the lanthanide series. Lanthanide elements with a smaller ionic radius stabilize the orthorhombic phase to higher temperatures and lower oxygen content.
The 4f electrons of the lanthanide series of the elements (La - Lu), being well shielded by intervening electron shells, are largely unreactive with neighboring ligands.