chapter  15
6 Pages

Families of elements: the periodic table

However, as we move from left to right within a period the atomic radius decreases: therefore the forces of attraction between electron and nucleus increase, and it follows that ionization potential also increases. The decrease in atomic radius from left to right in a period may seem counterintuitive as electron number is increasing in this direction. However, the radius decreases because of the increasingly large forces exerted by the atomic nucleus as proton number increases, and these cause a reduction in atomic radii.