Given the shell model of the atom, suggest a possible reason that Lewis proposed a maximum of two electrons for hydrogen and a maximum of eight electrons for carbon, nitrogen, oxygen, and fluorine.

Answer 1

hard to say, since Fluorine has nine electrons.

shell #n can hold up to 2n^2 electrons, so the shells hold 2,8,18,32, and so on

Answer 2

I think the question means 8 electrons for C, N, O, F in the outside shell. Two electrons in the 1st shell and it will be filled and 8 electrons in the 2nd shell and it will be filled. So F with 9 total gives 2 in the 1st shell and 7 in the 2nd shell. With just one more electron in the 2nd shell F can attain a stable configuration. That's why F occurs as F2.