On the periodic table, period 2 and 3, 4 and 5, 6 and 7 and so on have similar blocks, identical length and groups. What are such pairs of analogous periods called?

  • 2
    $\begingroup$ This is an interesting question. I am not sure these pairs of periods have any special names, but I would love to learn otherwise. $\endgroup$
    – Ben Norris
    Commented Nov 21, 2013 at 15:20
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    $\begingroup$ I agree with @BenNorris, the periods as such are referred to usually by number, the 2nd period is known among theoretical chemists as "light elements", but groups of periods are of no importance, afaik. $\endgroup$
    – ssavec
    Commented Nov 21, 2013 at 15:52

1 Answer 1


In a bit of a web search, there does not seem to be any particular names for families of periods in the Periodic Table. However, according to WebElements,

The f-block elements are assigned to Periods 6 (lanthanoids) and 7 (actinoids) since that is where they are located in the full, or extended, version of the periodic table.

However, these, according to the image below, only apply to the Lanthanides and Actinides, not all of periods 6 and 7.

enter image description here

Image source


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