A specific aqueous complex relies on the central nickel cation () for its structural and magnetic pr — d and f Block Elements Chemistry Question
Question
A specific aqueous complex relies on the central nickel cation ($Ni^{2+}$) for its structural and magnetic properties. Calculate the exact mathematical value of the squared spin-only magnetic moment ($\mu^2$) in squared Bohr Magnetons (B.M. $^2$) for this isolated central $Ni^{2+}$ ion.
💡 Solution & Explanation
The atomic number of Nickel ($Ni$) is $28$, giving it a ground-state electronic configuration of $[Ar] 3d^8 4s^2$. When ionized to strictly $Ni^{2+}$, it sheds its $4s$ electrons entirely, resulting in a $[Ar] 3d^8$ configuration. Following Hund's rule for filling five degenerate $d$ -orbitals, six electrons pair up in three orbitals, leaving exactly $2$ unpaired electrons ($n = 2$). The spin-only magnetic moment formula is $\mu = \sqrt{n(n + 2)}$. Substituting $n = 2$ yields $\mu = \sqrt{2(2 + 2)} = \sqrt{8}$. Therefore, the squared value, $\mu^2$, is exactly $8$.