Determine the total sum of all unpaired electrons present in the ground state electronic configurati — Atomic Structure Chemistry Question

💡 Solution & Explanation

First, determine the electronic configurations of the divalent cations. $Fe^{2+}$ ($Z=26$): $[Ar] 3d^6 4s^0$. Filling the $5$ $d$ -orbitals yields $4$ unpaired electrons. $Co^{2+}$ ($Z=27$): $[Ar] 3d^7 4s^0$. Filling the $5$ $d$ -orbitals yields $3$ unpaired electrons. $Ni^{2+}$ ($Z=28$): $[Ar] 3d^8 4s^0$. Filling the $5$ $d$ -orbitals yields $2$ unpaired electrons. The total sum of unpaired electrons across all three species is $4 + 3 + 2 = 9$.