the m shell has the capacity of holding 18 electrons.then why does potassium have electronic configuration of 2,8,8,1 and not 2,8,9?

Asked by aashiya kanha sharma | 29th Dec, 2013, 01:30: PM

Expert Answer:

Potassium has 19 electrons and m shell is 3rd energy level.

Its electronic configuration is 1s22s22p63s23p6 4s1 instead of 1s22s22p63s23p6 3d1.

This is because of Afbau’s principle which states that electrons fill orbitals starting at the lowest available (possible) energy levels before filling higher levels (e.g. 1s before 2s and 4s before 3d).

As the energy of 3d orbital is higher than 4s, the last electron in potassium get accomadated in 4s energy level instead of 3d.


Answered by Prachi Sawant | 2nd Jan, 2014, 12:19: PM

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