Principle Quantum Number in D-Block  [ENDORSED]


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isauramora3K
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Joined: Fri Sep 29, 2017 7:07 am

Principle Quantum Number in D-Block

Postby isauramora3K » Sat Oct 28, 2017 12:16 pm

Why does the principle quantum number drop down by one when you reach the D-block?

Nancy Dinh 2J
Posts: 59
Joined: Fri Sep 29, 2017 7:07 am

Re: Principle Quantum Number in D-Block  [ENDORSED]

Postby Nancy Dinh 2J » Sat Oct 28, 2017 3:06 pm

The d-block actually belongs to the shell above, but because the energy difference between each principal level gets smaller and smaller as n increases, the electrons start to fill in the ns orbitals before they start filling in the (n-1)d orbitals.

(I like to think of it as the electrons getting confused because of the very small energy difference. Sort of like trying to see the difference between the colors peach and salmon.)

Vincent Kim 2I
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Re: Principle Quantum Number in D-Block

Postby Vincent Kim 2I » Sat Oct 28, 2017 4:01 pm

You start filling the 3d orbital after 4s because the 4s orbital generally has lower energy than the 3d orbital.

Justin Lai 1C
Posts: 50
Joined: Fri Sep 29, 2017 7:04 am

Re: Principle Quantum Number in D-Block

Postby Justin Lai 1C » Sun Oct 29, 2017 11:10 pm

Why do electrons fill up the 4s shells before the 3d shells in Potassium and Scandium if 3d is lower energy?

Nathan Tu 2C
Posts: 46
Joined: Fri Sep 29, 2017 7:07 am

Re: Principle Quantum Number in D-Block

Postby Nathan Tu 2C » Sun Oct 29, 2017 11:18 pm

The simple answer is that the energy difference is that the energy difference between 3d and 4s is so small, filling up 4s first happens to be more stable. With exception of Cu and Cr and elements similar to those.


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