The periodic table was arranged so that properties could be predicted for elements, just by looking at their position in relation to other elements. consider two of the group 2 elements, magnesium and strontium. which statement accurately describes the difference in the atomic radius? magnesium has a larger atomic radius because it has a lesser effective nuclear charge. strontium has a larger atomic radius because it contains more protons. magnesium has a smaller atomic radius because it has 2 valence electrons. strontium has a larger atomic radius because strontium has more shells of electrons than magnesium does.