Em tham khảo nha:
\(\begin{array}{l}
Fe:1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}3{d^6}4{s^2}\\
F{e^{2 + }}:1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}3{d^6}\\
F{e^{3 + }}:1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}3{d^5}\\
S:1{s^2}2{s^2}2{p^6}3{s^2}3{p^4}\\
{S^{2 - }}:1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}
\end{array}\)