The mg2 + and na + ions each have ten electrons. which ion would you expect to have the smaller radius? explain your choice

Mg2 + has the smaller radius because it has 12 protons where Na + has 11. Because of Coulomb’s Law (F=kQ1Q2/r^2) the more protons there are, the more strongly the nucleus pulls on the electrons. This keeps the electrons closer to the nucleus and thus has a smaller radius than Na + (which has fewer protons and thus a smaller attractive force between the protons and electrons).