How do you write the noble-gas electron configuration for manganese?

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Answer 1 · 2018-08-07T05:55:52

Well, $Z_"manganese"=25$ ... $Mn-=[Ar]4s^(2)3d^5$

...the nearest Noble gas is $"argon, Z=18"$ ..

And so we do not have to specify the configuration of the first 18 electrons, because these approximate the configuration of argon..

$underbrace(Z=18, 1s^(2)2s^(2)2p^(6)3s^(2)3s^(6))_"electronic configuration of argon"$

For manganese, $Z=25$

$underbrace(Z=25, 1s^(2)2s^(2)2p^(6)3s^(2)3s^(6))_"electronic configuration of argon"4s^(2)3d^5$

And so finally... $Mn-=[Ar]4s^(2)3d^5$

And clearly all the chemical action takes place with the valence electrons...