lanthanide series definition of lanthanide series in the Free Online Encyclopedia.

lanthanide series, a series of metallic elements, included in the rare-earth metals rare-earth metals, in chemistry, group of metals including those of the lanthanide series and actinide series , usually yttrium , sometimes scandium and thorium , and rarely zirconium .
..... Click the link for more information. , in Group 3 of the periodic table periodic table, chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley . In the periodic table the elements are arranged in columns and rows according to increasing atomic number (see the
..... Click the link for more information. . Members of the series are often called lanthanides, although lanthanum lanthanum (lăn`thənəm) [Gr.,=to lie hidden], metallic chemical element; symbol La; at. no. 57; at. wt. 138.9055; m.p.
..... Click the link for more information. (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 cerium (sēr`ēəm) [from the asteroid Ceres], metallic chemical element; symbol Ce; at. no. 58; at. wt. 140.12; m.p. 799°C;; b.
..... Click the link for more information. , praseodymium praseodymium (prā'zēōdĭm`ēəm, –sēō–) [Gr.
..... Click the link for more information. , neodymium neodymium (nē'ōdĭm`ēəm), metallic chemical element; symbol Nd; at. no. 60; at. wt. 144.24; m.p. about 1,021°C;; b.
..... Click the link for more information. , promethium promethium (prōmē`thēəm), artificially produced radioactive chemical element; symbol Pm; at. no. 61; mass no.
..... Click the link for more information. , samarium samarium (səmâr`ēəm), metallic chemical element; symbol Sm; at. no. 62; at. wt. 150.36; m.p. 1,072°C;; b.p.
..... Click the link for more information. , europium europium (y
..... Click the link for more information. , gadolinium gadolinium (gădəlĭn`ēəm), metallic chemical element; symbol Gd; at. no. 64; at. wt. 157.25; m.p. 1,312°C;; b.p.
..... Click the link for more information. , terbium terbium (tûr`bēəm) [from Ytterby, a village in Sweden], metallic chemical element; symbol Tb; at. no. 65; at. wt. 158.
..... Click the link for more information. , dysprosium dysprosium (dĭsprō`zēəm) [Gr.,=hard to get at], metallic chemical element; symbol Dy; at. no. 66; at. wt. 162.50; m.p.
..... Click the link for more information. , holmium holmium (hōl`mēəm) [Lat.,=Stockholm], metallic chemical element; symbol Ho; at. no. 67; at. wt. 164.9304; m.p.
..... Click the link for more information. , erbium erbium (ûr`bēəm) [from Ytterby, a town in Sweden], metallic chemical element; symbol Er; at. no. 68; at. wt. 167.26; m.
..... Click the link for more information. , thulium thulium (th
..... Click the link for more information. , ytterbium ytterbium (ĭtûr`bēəm) [for Ytterby, a town in Sweden], metallic chemical element; symbol Yb; at. no. 70; at. wt. 173.
..... Click the link for more information. , and lutetium lutetium, formerly lutecium (both: l
..... Click the link for more information. . 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.

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.