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?
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.