HardChemistryHigh School (11–12)The d- and f-Block Elements › Lanthanoids and Actinoids (f-Block)NumericalConceptualA-Level IB NEET

Dysprosium has atomic number 66. Find the number of 4f electrons in Dy³⁺ and in Dy⁴⁺, and the…

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Dysprosium has atomic number 66. Find the number of 4f electrons in $\text{Dy}^{3+}$ and in $\text{Dy}^{4+}$ , and the number of unpaired electrons in $\text{Dy}^{3+}$ . Compare $\text{Dy}^{4+}$ with $\text{Ce}^{4+}$ and say which is likely to be the easier to form.

Need a reminder? The key ideaShow

The 3+ ion of a lanthanoid is $[\text{Xe}]\,4f^{n}$ with $n = Z - 57$ . Unpaired electrons: $n$ up to 7, then $14 - n$ . Spin-only moment: $\mu = \sqrt{n(n+2)}\ \text{BM}$ . An empty, half-full or full 4f subshell ( $4f^0$ , $4f^7$ , $4f^{14}$ ) makes an ion unusually stable. That explains $\text{Ce}^{4+}$ , $\text{Tb}^{4+}$ , $\text{Eu}^{2+}$ and $\text{Yb}^{2+}$ . For a cell, $\Delta G^\circ = -nFE^\circ$ with $F = 96.5\ \text{kJ/(V mol)}$ .

The worked solution

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