Answer
(a) I$^{1-}$
(b) Mg$^{2+}$
(c) O$^{2-}$
(d) Na$^{1+}$
Work Step by Step
(a) I$^{1-}$
The elemental symbol for iodine is I. Iodine is in group 17; therefore, it has a valence of 1-.
(b) Mg$^{2+}$
The elemental symbol for magnesium is Mg. Magnesium is in group 2; therefore, it has a valence of 2+.
(c) O$^{2-}$
The elemental symbol for oxygen is O. Oxygen is in group 16; therefore, it has a valence of 2-.
(d) Na$^{1+}$
The elemental symbol for sodium is Na. Sodium is in group 1; therefore, it has a valence of 1+.
