An atom’s oxidation number changes from –2 to –5. Was the atom oxidized or reduced, and how many electrons were required for the change?

Question

A. Oxidized, 2 electrons

B. Oxidized, 3 electrons

C. Reduced, 2 electrons

D. Reduced, 3 electrons

E. None of the Above

Answer 1

Yes! This is correct. Reduction is the process of gaining electrons, and since the oxidation number (which is the same as the ionic charge) changes from -2 to -5, the ion is getting more negative—has more electrons. It requires three more electrons to get from a charge of -2 to -5.