Weird Electron Configuration of some elements . . . Help:(

[Versati1ity]

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What's up with Cr, Mo, Ru, Rh, Pd, Pt, Cu, Ag, and Au? They fill their d orbital first then their S orbital leaving 1 unpaired electron in their s orbital. All the other transition elements don't do this and fill their s orbitals first. Do you guys think this should be memorized?


I know the (n+l) rule and that when you write out their electron configuration the 3d comes before the 4s, but for all transition elements except for the ones I listed the s orbital is filled s^2 and the d orbital is left with unpaired electrons (if applicable). So why do those elements I listed fill d first then s?

 

[yakuza]

What's up with Cr, Mo, Ru, Rh, Pd, Pt, Cu, Ag, and Au? They fill their d orbital first then their S orbital leaving 1 unpaired electron in their s orbital. All the other transition elements don't do this and fill their s orbitals first. Do you guys think this should be memorized?


I know the (n+l) rule and that when you write out their electron configuration the 3d comes before the 4s, but for all transition elements except for the ones I listed the s orbital is filled s^2 and the d orbital is left with unpaired electrons (if applicable). So why do those elements I listed fill d first then s?

The exceptions for the transition metals are column 6 and column 11
column 6: Cr, Mo, and W will have up to 3d4..BUT these exception columns want to have half-filled subshells and filled subshells.

OK so Cr will be [Ar]4s2,3d4 BUT it wants to be half filled, so the d steals 1e- from the s making it [Ar]4s1,3d5

Then the same for column 11 except they want have fully filled things.

I hope that's what your looking for.

 

[doc3232]

The exceptions for the transition metals are column 6 and column 11
column 6: Cr, Mo, and W will have up to 3d4..BUT these exception columns want to have half-filled subshells and filled subshells.

OK so Cr will be [Ar]4s2,3d4 BUT it wants to be half filled, so the p steals 1e- from the s making it [Ar]4s1,3p5

Then the same for column 11 except they want have fully filled things.

I hope that's what your looking for.

Thanks man.
Kaplan gave an example of on of these.
What about V, Nb, Ta etc columns 3 and 8.
Do they also steal two electrons from the s or not?
This always confused me, no book says they don't...

 

[Versati1ity]

The exceptions for the transition metals are column 6 and column 11
column 6: Cr, Mo, and W will have up to 3d4..BUT these exception columns want to have half-filled subshells and filled subshells.

OK so Cr will be [Ar]4s2,3d4 BUT it wants to be half filled, so the p steals 1e- from the s making it [Ar]4s1,3p5

Then the same for column 11 except they want have fully filled things.

I hope that's what your looking for.

But Cr electron configuration is [Ar] 3d^5 4s^1, where did you get the p from?

 

[yakuza]

oh sorry. I meant to say d

 

[yakuza]

Thanks man.
Kaplan gave an example of on of these.
What about V, Nb, Ta etc columns 3 and 8.
Do they also steal two electrons from the s or not?
This always confused me, no book says they don't...

Nahh 3 and 8 don't do anything. Only column 6 and 11

 

[Versati1ity]

oh sorry. I meant to say d

Ok I think I actually might understand it now. So what you're saying is the electron configuration of Cr without the borrowing (stealing) of electrons would be [Ar] 4s^2 3d^4 but that places Cr with one completely vacant electron orbital. I assume this is a very bad thing for stability purposes, so it takes an electron from the 4s orbital which would be stable enough with only 1 electron in it in order to place an electron in each of the five 3d orbitals, therefore making it more stable.

Am I right?

 

[Versati1ity]

Dude yakuza thanks a lot man! I went through the same thing with Cu and so copper needs to take an electron from the 4s orbital because without it copper has 4 d orbitals filled and 1 orbital with an unpaired electron. I guess by adding the electron from the 4s orbital the 5 d orbitals all contain paired electrons and the configuration is much more stable. I am right?

BTW, let me know if any of my understanding is wrong in my above post.

 

[jdent]

This is known as the bad ass elements. However there is no need for memorizing it. Just understand it. If promoting one electron from te s to the d will stabilize the atom, then its wort it to excite the s electron. Sometimes you got to spend to receive.

 

[klutzy1987]

Just understand that anyhing that should end in d4 or d9 will instead be bumped up.

 

[benatious41]

Just understand that anyhing that should end in d4 or d9 will instead be bumped up.

But are there anything that bump down like the column with Fe? It has 6 in its d, shouldn't it try to have 5?

 

[BrazilianRider]

But are there anything that bump down like the column with Fe? It has 6 in its d, shouldn't it try to have 5?

I don't think so... what would it do with that extra electron? It has nowhere to put it, so it's SOL.