I could rearrange these two but in most of chemistry what matters is what's in the outter shell so it's interesting that although with filled outer 4s2 here and then we kept adding more and more electrons, those electrons where just filling a lower energy shell, so if we.. in this atom, in case of Iron, when we talk about the electrons in this outer energy shell and thoses are called the Valence Electrons and these are the ones that react.