Which property do the elements in each column of the representative elements series of the periodic table have in common?

Question

number of valence electrons
number of orbitals
number of protons
number of neutrons

Answer 1

The elements in each column (or group) of the representative elements series of the periodic table have in common the number of valence electrons.

For example, all elements in Group 1 have one valence electron, all elements in Group 2 have two valence electrons, and so on. This similarity in valence electron count contributes to the similar chemical properties of the elements within the same group.