4s or 3d

[rainashley]

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4s or 3d?
which one has lower energy? which one fills first? why?

 

[PiBond]

4s or 3d?
which one has lower energy? which one fills first? why?

4s level is filled before 3d...4s has lower energy.

also know that when we remove an electron that they get removed from 4s before 3d because of half-filled d stability

 

[rainashley]

so 4s gets filled and removed from first? 4s is also lower in energy?
why?

 

[PiBond]

so 4s gets filled and removed from first? 4s is also lower in energy?
why?

4s is lower in energy than 3d because the average position of the electron in 4s is closer to the nucleus than in 3d...this equates to lower energy

 

[Isoprop]

also know that when we remove an electron that they get removed from 4s before 3d because of half-filled d stability

Actually, 4s always gets removed before 3d even when there isn't half-filled or filled d orbitals.

 

[Isoprop]

so 4s gets filled and removed from first? 4s is also lower in energy?
why?

The reason why is beyond the scope of the MCAT. Just remember that 4s fills before 3d, but 4s electrons are removed first when transition metals ionize.

(Note: chemists today are still debating why this happens).