2,8.3 (3rd shell still filling)
ELECTRON SHELL RULES:
1) Electrons always occupy shells (sometimes called energy levels.)
2) The lowest energy levels are always filled first these are the ones close to the nucleus.
3) Only a certain number of electrons are allowed in each shell:
1st shell: 2 2nd shell: 8 3rd shell: 8
4) Atoms are much happier when they have full electron shells like the noble gases in group 0.