why does potassium with atomic number as 19 have its electronic configuration as 2,8,8,1 .why it doesnot not have an electronic configuration of 2,8,9 , if the M shell can accommodate 18 electrons ?

Asked by  | 6th Oct, 2011, 12:00: AM

Expert Answer:

Potassium with atomic number as 19 have its electronic configuration as 2,8,8,1 not as 2,8,9 because the  energy of 4s orbital is less than 3d orbital,so 4s orbital is filled first.
Therefore, the electronic configuration of potassium is 1s2 2s2 2p6 3s2 3p6 4s1 (2,8,8,1) but not as 1s2 2s2 2p6 3s2 3p6 3d1(2,8,9)

Answered by  | 7th Oct, 2011, 09:19: AM

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