The period is the # of energy levels that element has.
The period tells you if the elements are the same or different.
The period tells you if the elements are the same or different.
The group is the # of valence Electrons
In the periodic table the group are on the outer shell of the atom.
In the periodic table the group are on the outer shell of the atom.
The elements are classified by their valence electrons because it shows what group its in.