Question

The electronic configuration of bivalent Europium and trivalent Cerium, are: (Atomic Number : $\mathrm{Xe}=54,\mathrm{Ce}=58,\mathrm{Eu}=63$)

• A. $\left[Xe\right]4f^7,\left[Xe\right]4f^1$
• B. $\left[Xe\right]4f^{7}6s^2,\left[Xe\right]4f^{2}6s^2$
• C. $\left[Xe\right]4f^2,\left[Xe\right]4f^7$
• D. $\left[Xe\right]4f^4,\left[Xe\right]4f^9$

Answer 1

The correct option is A

$\left[Xe\right]4f^7,\left[Xe\right]4f^1$

Explanation of the correct option:

The correct answer is option A:

The atomic number of Cerium is 58 and Europium is 63.

The electronic configurations of bivalent europium and trivalent cerium are,

$$\begin{gathered} Ce\left(58\right):\left[Xe\right]6{\mathrm{s}}^{2}4{\mathrm{f}}^2(g.s) \\ {\mathrm{Ce}}^{3+}:\left[\mathrm{Xe}\right]4{\mathrm{f}}^1 \\ Eu\left(63\right):\left[Xe\right]6{\mathrm{s}}^{2}4{\mathrm{f}}^7(g.s) \\ {\mathrm{Eu}}^{2+}:\left[Xe\right]4f^{\mathit{7}} \end{gathered}$$

Hence, option A is correct.
The electronic configuration of bivalent europium and trivalent cerium, are $\left[Xe\right]4f^7,\left[Xe\right]4f^1$.