If eight is the key number in the periodic table, then why aren't there eight rows?

Answer 1

Each row(horizontal) on the periodic table is the filling of an electron ring. There can be 7 rings.
Each column is a family with similar characteristics because they have the same number of electrons in the outer ring.
The magic number ,8, is a stable number for elements to have. It represents filling the first 2 sublevels in the different energy levels, s and p.Elemens are stable at this level. It is not related to how many rings they have.