April 08, 2020, 11:48:46 PM
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Topic: Atomic orbitals confusion  (Read 369 times)

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Offline Lewis

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Atomic orbitals confusion
« on: December 18, 2019, 12:47:47 PM »
Hi.

I'm confused about filling 3d and 4s subshells. When writing electrons configuration for transition metal (for example), why do we fill 4s before 3d, yet when this same metal atom gets ionized, 4s electrons are removed first (assuming that 4p isn't filled)?

Also, why do subshells become more stable when they are half-filled or fully-filled with electrons?

What I think:
- 4s is higher than 3d, but 3d extends more away from the nucleus than 4s does.
- Half filled: because they don't face repulsion force from another electron in the same orbital maybe?

Offline Corribus

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Re: Atomic orbitals confusion
« Reply #1 on: December 18, 2019, 02:50:34 PM »
You can't treat the orbital energies as though they are static things. When you remove an electron from a shell, it affects the energies of all the other orbitals. The situation also changes when the core nuclear charge changes. As to why the orbital energies fill up in an unexpected order, here is a useful reference:

https://www.chemguide.co.uk/atoms/properties/3d4sproblem.html
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

Offline Lewis

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Re: Atomic orbitals confusion
« Reply #2 on: December 21, 2019, 11:38:39 AM »
You can't treat the orbital energies as though they are static things. When you remove an electron from a shell, it affects the energies of all the other orbitals. The situation also changes when the core nuclear charge changes. As to why the orbital energies fill up in an unexpected order, here is a useful reference:

https://www.chemguide.co.uk/atoms/properties/3d4sproblem.html
Sorry for the late reply, and thanks, that explains a lot.

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