Which of the following ionic species is NOT isoelectronic with the Neon (Ne) atom? — Atomic Structure Chemistry Question

💡 Solution & Explanation

Neon ($Z=10$) has 10 electrons. $O^{2-}$ has $8+2=10$ electrons. $F^{-}$ has $9+1=10$ electrons. $Mg^{2+}$ has $12-2=10$ electrons. However, $Cl^{-}$ ($Z=17$) has $17+1=18$ electrons. [35]