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Leah Thomas 2E
Posts: 51
Joined: Fri Sep 29, 2017 7:06 am


Postby Leah Thomas 2E » Fri Nov 03, 2017 12:56 am

Can someone explain why there are more exceptions when filling electrons for the lanthanides? Like there are more energy levels so they become closer and...
Just for context.

Leon Popa
Posts: 18
Joined: Fri Sep 29, 2017 7:04 am

Re: Lanthanides

Postby Leon Popa » Fri Nov 03, 2017 1:30 am

Hi Leah,

To answer this question, I used the diagram that Dr. Lavelle often illustrates when solving problems on the board. This diagram (shown below) indicates that as the principal quantum number (n) increases, the spacing between orbitals becomes smaller. This means that as n gets larger, it become easier for changes to happen in the electronic structure, which means that the orbital energy patterns may rearrange.

n=4 ____________________
n=3 ____________________

n=2 ____________________

n=1 ____________________

Elements in the Lanthanide and Actinide Series have large n quantum numbers, the Lanthanides being n=6 and Actinides n=7. So it doesn't take much for the order of orbital filling to change for these elements - there are more exceptions.

Hope that helps Leah.

- Leon

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