Lanthanoids and actinides

As lanthanides and actinides in to the periodic table of the chemical elements because of their similarity lanthanides and actinides summarized. Together they form the f- block . The elements are between the scandium group , the 3rd group of the periodic table, and the titanium group , the 4th group. The elements lanthanum (La) and actinium (Ac) are usually added to the lanthanoids and actinides in the periodic table, although they should correctly be included in the scandium group. However, the International Union of Pure and Applied Chemistry decided to class them among the lanthanoids and actinides through practical use. Lanthanoids and actinides belong to the group of metals and have a metallic sheen and high conductivity . With promethium ( atomic number 61) one of the two radioactive elements with an atomic number less than 83, from which all elements are radioactive, belongs to the lanthanoids. The actinides are therefore also all radioactive, which is symbolized by a red border in the section of the periodic table below. The actinides with an atomic number greater than 95 are artificial elements , symbolized by the dashed border.

Section from the periodic table
Lanthanoids			57 La	58 Ce	59 Pr	60 Nd	61 pm	62 Sm	63 Eu	64 Gd	65 p	66 Dy	67 Ho	68 he	69 Tm	70 yb	71 Lu
Actinoids			89 Ac	90 th	91 Pa	92 U	93 Np	94 Pu	95 am	96 cm	97 Bk	98 Cf	99 it	100 m	101 Md	102 No.	103 Lr

Individual evidence

1. ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , pp. 1721-1723.
2. ^ Richard B. Dickerson, Harry B. Gray, Marcetta Y. Darensbourg, Donald J. Darensbourg: Principles of Chemistry . 2nd Edition. Walter de Gruyter, Berlin / New York 1988, ISBN 978-3-11-009969-0 , p. 423 ( limited preview in Google Book search).