Question

fill in the blanks
the periodic table of the elements has vertical that tell you the number of and horizontal that tell you the number of.
electron shells electrons groups valence periods

Explanation:

In the periodic table, vertical columns are called groups. The group number indicates the number of valence electrons (for main - group elements). Horizontal rows are called periods. The period number indicates the number of electron shells an atom of the element has.

Answer:

The Periodic Table of the Elements has vertical groups that tell you the number of valence electrons and horizontal periods that tell you the number of electron shells.