In what respect does an atom of magnesium differ from a magnesium ion (Mg^{2+})?
(A)The ion has a more stable electronic arrangement than the atom.
(B)The positive charge on the nucleus of the ion is two units greater than the nuclear charge on the atom.
(C)The ion has two more protons than the atom.
(D)The ion will react more readily with free Cl₂.
(E)The ion has two more planetary electrons than the atom.
Can anyone explain this one?