Question

From the following pairs of ions which one is not an iso-electronic pair?

• A. $O^{2-},F^{-}$
• B. $N{a}^{+},M{g}^{2+}$
• C. $M{n}^{2+},F{e}^{3+}$
• D. $F{e}^{2+},M{n}^{2+}$

Answer 1

Answer: (D)

Isoelectronic refers to two atoms, ions, or molecules that have the same number of total electrons and the same number of valence electrons. (a) $O^{2-}$ and $F^{-}$both have 10 electrons (b) $N{a}^{+}$and $M{g}^{2+}$ both have 10 electrons (c) $M{n}^{2+}$ and $F{e}^{3+}$ both have 23 electrons (d) $F{e}^{2+}$ has 24 electrons. $M{n}^{2+}$ has 23 electrons.