Why Are Lanthanides and Actinides Excluded from the Periodic Table?

[faiz4000]

why aren't the lanthanide and actinide series included in the periodic table? is there some non periodicity in there elements?

 

[Mapes]

Are you asking why these series are shown at the bottom? It's a http://en.wikipedia.org/wiki/Extended_periodic_table" .

 

[faiz4000]

yes,i am trying to say why they are not in the main periodic table? why you can't assign there elements to any group? Is there any non-periodicity in the elements?

 

[Mapes]

Did you read the link? The f-block elements don't currently have group numbers, though this may change in the future. (Group numbers are just a convention anyway, independent of the physics.) http://www.meta-synthesis.com/webbook/35_pt/pt_database.php?PT_id=204"'s another.

 

[Raphie]

why aren't the lanthanide and actinide series included in the periodic table? is there some non periodicity in there elements?

The format of the periodic table is "arbitrary," not in the sense that it makes no sense, but from a Sociology/Psychology of Science perspective in the sense that the manner in which it is presented is guided by the human tendency to categorize in groups with linkage to other areas of human understanding. How we, as products of nature, group the elements may or may not be how nature in its raw form groups them (most likely not...). In other words, our periodic table is an imperfect, but extremely useful model. There are others. See...

Alternative Periodic Tables
http://en.wikipedia.org/wiki/Alternative_periodic_tables