How is atomic structure related to the periodic table?
The number of outer shell electrons determines the group number of the element.
The number of occupied principle quantum shells (energy levels) determines the period of the element.
The proton number determines the element itself and its position.
Sodium has 11 protons so you can right away tell where it is. If you look into its electronic configuration, that is, 2,8,1. You can tell that since it has one outer electron, it is in group 1. And since it occupies three shells, it's in period 3.