What is similar between elements in the same vertical column?
The valance electron formation.
elements in the same vertical column also called families or groups have the same number and arrangements of valance electrons.
Group VII A for an example
Fluorine in the second period has seven electrons and a normal charge of -1
Chlorine in the third period has seven electrons has a normal charge of -1 but can also be +1, +3. +5 and +7
This pattern continues for the rest of this vertical family.