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The INTERNET Database of Periodic Tables

There are thousands of periodic tables in web space, but this is the only comprehensive database of periodic tables & periodic system formulations. If you know of an interesting periodic table that is missing, please contact the database curator: Mark R. Leach Ph.D.

Use the drop menus below to search & select from the more than 1300 Period Tables in the database: 

  Text Search:       

Year:  2010 PT id = 371

Scandium Group and The Periodic Table: Sc, Y, Lu, Lr   or   Sc, Y, La, Ac?

Pieter Thyssen and Koen Binnemans discuss (CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis) the confusion surrounding the members of and the positioning of the scandium group. There are three forms commonly used.

A medium-long form and long form depiction of the 15LaAc periodic table. As should be clear from the long form periodic table, an intermingling occurs between the f-block and d-block:


A medium-long form and long form depiction of the 14CeTh periodic table. The d-block has been torn apart in the long form, due to the insertion of the f-block:


A medium-long form and long form depiction of the 14LaAc periodic table. The 14LaAc periodic table is in perfect agreement with the Madelung rule:

A recent graphic posted by Eric Scerri:

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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –

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