When I have a gadolinium ion ($\ce{Gd^3+}$), how can I calculate its electron configuration?

$$\ce{Gd} : \mathrm{[Xe] (4f)^7 (5d)^1 (6s)^2}$$

Do I need to first subtract the 2 electrons in the $\mathrm{s}$-orbital and then the $\mathrm{d}$-/$\mathrm{f}$-orbital?

  • 5
    $\begingroup$ When determining electron configurations of cations, one takes the electron configuration of the neutral atom, and then starts removing electrons from the orbital with highest n value. If there is a tie, you then choose the orbital with highest l value. $\endgroup$ Aug 16, 2013 at 12:53

1 Answer 1


I agree with bobthechemist's comment.

When you are determining the electronic configuration of anions/cations, you will first need to determine electronic configuration of neutral atom. Like in the case above:

$$\ce{Gd} : \mathrm{[Xe] (6s)^2 (4f)^7 (5d)^1}$$

Now arrange this configuration according to ascending value of $n$:

$$\mathrm{[Xe] (4f)^7 (5d)^1 (6s)^2}$$

Now, according to your need start subtracting electrons from highest value of $n$, like for $\ce{Gd^3+}$, the electronic configuration will be:

$$\ce{Gd^3+} : \mathrm{[Xe] (4f)^7}$$

See this to know more on calculating electronic configuration of cations and anions.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy