Question

what shell contains the valence electrons for an aluminum atom?
middle shell
innermost shell
outermost shell

Explanation:

Valence electrons are the electrons in the outermost shell (also called the valence shell) of an atom. For an aluminum atom, its electron configuration is \(1s^2 2s^2 2p^6 3s^2 3p^1\), so the outermost shell (n = 3) contains the valence electrons. The "middle shell" and "innermost shell" do not hold valence electrons as valence electrons are defined as those in the outermost energy level involved in chemical bonding.

Answer:

C. outermost shell (assuming the options are labeled A: middle shell, B: innermost shell, C: outermost shell; if the original options had different labels, adjust accordingly, but based on the content, the correct one is the outermost shell option)