Question

Why can't calcium have more than 8 electrons in the third shell but Zinc can have 18?

Answer 1

Answer:

Because calcium gets stable with 8 electrons......You will study the whole concept in +1

Answer 2

Answer:

The third shell of an atom has 18 electrons only not 8 electrons. You might be confused because first the electrons of 4s are filled and then the 10 electrons of 3d shells are filled. They are filled because of the n-l rule.

or

Electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels. In this way, the electrons of an atom or ion form the most stable electron configuration possible.” ... This is the reason for Calcium to have a configuration of 2,8,8,2 instead of 2,8,10