Writing Electron Config for Chromium after being ionized once?

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Yashaswi Dis 1K
Posts: 56
Joined: Fri Sep 29, 2017 7:04 am

Writing Electron Config for Chromium after being ionized once?

Postby Yashaswi Dis 1K » Tue Oct 31, 2017 10:03 pm

Hi, so I know that chromium's e-config is: [Ar](3d^5)(4s^1) as it is one of the exceptions to the e-configuration. When that element is ionized and becomes an ion (Cr^+1), which is the correct e-config?:

(1) [Ar](3d^5)...because the electron is removed from the s-orbital?

or

(2) [Ar](3d^4)(4s^1)...because the electron is removed from the d-orbital?

I am not sure because I knew that s-orbitals get filled first, but in this case w/ the extra space in d-orbitals, Chromium wants to have half-filled orbitals for stability, so is the number (1) option correct? At least that's what I think, b/c (Cr^+1) will want to have half-filled d-orbitals rather than have that extra s-orbital. Please let me know which option is correct for (Cr^+1) and the reason behind that. Also, does the reasoning which will be provided apply to all elements in the d-block instead of just chromium. Please let me know.

Thank you.

-Yashwi

Jessica Nunez 1I
Posts: 58
Joined: Thu Jul 13, 2017 3:00 am

Re: Writing Electron Config for Chromium after being ionized once?

Postby Jessica Nunez 1I » Tue Oct 31, 2017 11:30 pm

I would say that option 1 is correct because the correct electron configuration of Chromium is [Ar](3d^5)(4s^1). When the electron is ionized, the electron taken out is from the s-orbital.

I believe the reasoning will be provided for all elements in the d-block. However, we need to be most concerned about the elements that fall into the same group of Copper (Cu), Chromium (Cr), and Gold (Au).

Hope this helps!

Janine Chan 2K
Posts: 71
Joined: Fri Sep 29, 2017 7:04 am

Re: Writing Electron Config for Chromium after being ionized once?

Postby Janine Chan 2K » Tue Oct 31, 2017 11:40 pm

It should be (1). Higher energy electrons are removed first. In this case, the 4s electrons have a higher energy than 3d.


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