The calculated magnetic moment (in Bohr magnetons of $\mathrm{Cu}^{2+}$ ion is)

The calculated magnetic moment (in Bohr magnetons of $\mathrm{Cu}^{2+}$ ion is)
  1. $1.73$
  2. zero
  3. $2.6$
  4. $3.14$

Solution

Electronic configuration of $\mathrm{Cu}^{2+}$ is $1 s^2, 2 s^2, 2 p^6, 3 s^2, 3 p^6, 3 d^9$ (because $2 e^{-}$goes from $4 s$ orbital) Number of unpaired electrons $=1$ $ \begin{aligned} \text { Magnetic moment } & =\sqrt{n(n+2)} \\ & =\sqrt{1(1+2)} \\ & =\sqrt{3}=1.732 \end{aligned} $

Asked in: AP EAMCET 2002

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