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Which electrons react in a transition metal?

Discussion in 'MCAT Study Question Q&A' started by stester77s, 05.18.14.

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  1. stester77s

    stester77s 2+ Year Member

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    Take Ti, which has the electron configuration [AR] 3d2 4s2.


    Which electrons react to form bonds, and which electrons are lost first when Ti becomes oxidized? Is it the electrons in the 3d2 orbital AND the ones in the 4s2 orbital, or only 3d2?

    I also just want to ask another simple question, which is the convention to write the 3d orbital electrons before the 4s? Does that mean that in transition metals the d orbitals actually get filled before the s orbitals?
     
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  3. Teleologist

    Teleologist 2+ Year Member

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    Oops; knowledge is contained in below post.
     
    Last edited: 05.18.14
  4. Teleologist

    Teleologist 2+ Year Member

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    The valence electrons, of course.

    The electrons furthest away from the nucleus are lost first.

    Go for it.

    Lower energy orbitals are populated first. This is the Aufbau (German for "build-up") principle.
     
  5. stester77s

    stester77s 2+ Year Member

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    Thanks, but you entirely ignored my question. "Is it the electrons in the 3d2 orbital AND the ones in the 4s2 orbital, or only 3d2?" Do both or only one of these groups of electorns participate in bonding?

    Thanks again, but entirely not helpful. I am asking a specific question. When Ti gets oxidized, which electrons are lost first. The 4s electrons or the 3d electrons. And can 4s electrons ever be lost when Ti gets oxidized?

    Again, thanks, but you did not answer my question. "Does that mean in transition metals the d orbitals actually get filled before the s orbitals?"
     
    Last edited: 05.18.14
  6. Teleologist

    Teleologist 2+ Year Member

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    What's a 3d2 orbital? What's a 4s2 orbital?
     
  7. stester77s

    stester77s 2+ Year Member

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    3d and 4s orbitals respectively.

    3d2 and 4s2 are the electron configurations.
     
  8. Teleologist

    Teleologist 2+ Year Member

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    I can tell.

    Which ones are located furthest from the nucleus on a time-average basis? Note that this is a restatement of my first answer.

    Which one is lower in energy? Note that this again is a restatement of my first answer.
     
  9. Teleologist

    Teleologist 2+ Year Member

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    Another restatement of my previous answer: which contain valence electrons? Note that this is also stuff that one can find in an elementary chemistry text.

    ----

    I'm here to facilitate learning, not to spew forth correctness.

    My experience has been that when people work for answers, they retain it better than if I hand them answers.
     
  10. stester77s

    stester77s 2+ Year Member

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    Then I am not seeking your help. This isn't your place to play high-school teacher or stroke your own ego. I am asking a specific question because it may help on a specific problem that will help me solidify another principle. Your pollution of this thread has not helped.
     
  11. lightblueskies

    lightblueskies 2+ Year Member

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    The filling of d orbitals vs s orbitals in transition metals, like almost every concept, is actually not as simple as the way it's taught in general chem, but for the purpose of the MCAT, you can say that: the 4s electrons are lost before the 3d electrons. However, for your other question, the 4s orbitals are filled first when moving along the periodic table. But they will still be lost before the 3d electrons, and the 4s electrons are considered to be at a higher energy level in that regard. As you can see, both these explanations are kind of opposed to each other, but that's the way it's normally taught. Most important is to know that the 4s electrons are lost first and will participate in bonding before the 3d orbital electrons, but the 3d orbital electrons can also participate in bonding.
     
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  12. Teleologist

    Teleologist 2+ Year Member

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    That's what appears to happen when you follow the periodic table mechanically but that's not what physically happens.
     
  13. lightblueskies

    lightblueskies 2+ Year Member

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    I think that was made pretty clear when I said "moving across the periodic table" - i.e. not in a given transition metal. In Calcium, the 4s orbitals are filled, not the 3d. In this way, the 4s orbitals will be filled first "when moving across the periodic table." In a transition metal, 4s orbitals actually will have higher energy, which will change the way they are filled, and reflect the [AR] 3d2 4s2 notation for Ti. In addition, the filling of orbitals in a transition metal is an academic exercise to explain electron configuration, not what physically happens. BTW, your answers appear quite antagonistic and are not very helpful, as though you're trying to prove how smart you are.
     
  14. Teleologist

    Teleologist 2+ Year Member

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    You're right, I apologize if I hurt your feelings.
     
  15. lightblueskies

    lightblueskies 2+ Year Member

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    Lol! You didn't, no worries. :)
     
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  16. chemtopper

    chemtopper online organic/general chem/MCAT/DAT tutor 5+ Year Member

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    The outermost shell electrons will react first and those electrons are 4s2 because after filling of s and d orbitals ,4s becomes higher in energy then 3d so they are removed first . 3d are removed only after removal of 4s.
     
  17. jebelali

    jebelali 5+ Year Member

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    From what I understand, it is harder to extract d subshell electrons so in transition metals, the S subshell electors are lost first followed by d subshell (if need be).
     
  18. chemtopper

    chemtopper online organic/general chem/MCAT/DAT tutor 5+ Year Member

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    4s has higher principal quantum number 4 and 3d has lower principal quantum number 3.When 3d is empty it is higher in energy than 4s orbital because it is more diffused so more away from the nucleus.However when it is filled with electrons then it comes closer to the nucleus due to electrons present in it.So it will be harder to remove electrons from 3d and easy to remove electrons from 4s which is the outermost orbital of the element.
     
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  19. TheRelevant

    TheRelevant 2+ Year Member

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    Thanks a bunch! FINALLY found a good explanation after half an hour of digging. I was hoping you might also confirm my statement below? It would be very much appreciated!

    I am assuming that in most atoms below period 3 (well even sulfur and phosphorus do this, but still), the gained stability of the filled d-orbital is what causes the s- and p-orbitals to act as valence electrons? Hence the octet rule. But then again, there are exceptions to the octet rule and those must involve a reversal of d-orbital stability and participation of d-orbital electrons as valence electrons.
     
    Last edited: 06.17.14

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