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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: kimi85 on June 30, 2007, 09:55:41 AM

Title: electronic configuration and determining the number of unpaired electrons
Post by: kimi85 on June 30, 2007, 09:55:41 AM

Given is Fe3+

How many unpaired electrons are there?

What I did is I first wrote the electronic configuration.  Based on the electronic configuration I did, I thought there are 3 unpaired electrons.  But the correct answer is there are 5 unpaired electrons.

I hope someone could explain this to me.

Title: Re: electronic configuration and determining the number of unpaired electrons
Post by: Yggdrasil on June 30, 2007, 10:51:55 PM

Can you show the electron configuration you made?

Title: Re: electronic configuration and determining the number of unpaired electrons
Post by: kimi85 on July 01, 2007, 12:29:07 AM

1s²2s²2p⁶3s²3p⁶4s²3d³

Title: Re: electronic configuration and determining the number of unpaired electrons
Post by: Yggdrasil on July 01, 2007, 03:48:12 AM

For transition metal ions, all of the valence electrons go into the d orbital, so the electron configuration is [Ar]3d⁵.  I think has to do with the fact that the s-orbital electrons are more easily ionized than d-orbital electrons, but I'm not completely sure that this is a correct explanation.

Title: Re: electronic configuration and determining the number of unpaired electrons
Post by: kimi85 on July 01, 2007, 09:46:23 AM

Thank you very much. So, the two electrons at 4s will go to the 3d?
What will happen to 4s? Will it become 4s⁰?

Title: Re: electronic configuration and determining the number of unpaired electrons
Post by: Yggdrasil on July 01, 2007, 01:49:25 PM

Yes, the 4s orbital is unoccupied.

Title: Re: electronic configuration and determining the number of unpaired electrons
Post by: kimi85 on July 01, 2007, 08:45:58 PM

thank you very much  ;D