Question

Gadolinium belongs to 4f series. Its atomic number is 64. Which of the following is the correct electronic configuration of gadolinium?

• A. $\left[Xe\right]4f^{9}5s^1$
• B. $\left[Xe\right]4f^{7}5d^{1}6s^2$
• C. $\left[Xe\right]4f^{6}5d^{2}6s^2$
• D. $\left[Xe\right]4f^{8}6d^2$

Answer 1

The correct option is B $\left[Xe\right]4f^{7}5d^{1}6s^2$

You need to recall that Gd has a stable half filled 4f series. It is easy for lanthanides to have electrons jump between 5d, 4f and 6s due to the low energy gap betwen them.