Ferrus is a transition metal.
FeCl_2
Electronic configuration is given by
[tex]\\ \sf\longmapsto [Fe]^{2+}=1s^22s^22p^63s^23p^64s^23d^4[/tex]
FeCl_3
Electronic configuration is given by
[tex]\\ \sf\longmapsto [Fe]^{3+}=1s^22s^22p^63s^23p^64s^23d^3[/tex]