Question

elements like pottasium and calcium are electronically configured as 2,8,8,1 and 2,8,8,2 respectively. why not 2,8,9, and 2,8,10

Answer 1

1. This is because of the following rule in filling electrons:

"The maximum number of electrons that can be accommodated in the outermost orbit is 8."

2. Thus, the maximum electrons that can be accommodated in a valence shell is 8.

3. So, we see that if a shell has more than 8 electrons, then new valence shell is introduced.