Electron Configuration Exceptions:

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Sara Richmond 2K
Posts: 110
Joined: Fri Aug 30, 2019 12:16 am

Electron Configuration Exceptions:

Postby Sara Richmond 2K » Wed Oct 23, 2019 5:31 pm

Why fo the elements of Cr and Cu have different electron configurations than the rest of the elements in the 3d block? For instance why is Cr's electron configuration: [Ar]3d^5 4s^1 instead of [Ar]3d^4 4s^2? What other elements are an exception to the expected electron configuration? Will we need to memorize these?

Shivam Rana 1D
Posts: 106
Joined: Fri Aug 09, 2019 12:16 am

Re: Electron Configuration Exceptions:

Postby Shivam Rana 1D » Wed Oct 23, 2019 5:33 pm

An electron is moved from the s subshell to the d subshell when an atom is at d^4 because then all the subshells would be singly filled and this is more stable.

kristi le 2F
Posts: 102
Joined: Thu Jul 11, 2019 12:15 am

Re: Electron Configuration Exceptions:

Postby kristi le 2F » Wed Oct 23, 2019 6:12 pm

Half filled subshells and full filled subshells are more stable. For the d subshell, having 5 or 10 electrons in the subshell is favorable because it is a lower energy state.

Rachel Yu 1G
Posts: 113
Joined: Fri Aug 09, 2019 12:15 am

Re: Electron Configuration Exceptions:

Postby Rachel Yu 1G » Wed Oct 23, 2019 6:13 pm

d^5 and d^10 are two states where the element is stable because the electrons fill up half the orbital or the full orbital. Atoms want to achieve this state, so d^4 and d^5 use an electron from the s orbital to get to the half/full d orbitals, resulting in s^1 instead of s^2

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