From electron configurations
Fe(III) & Mn(II) both have 5 unpaired electrons spread across the 5 orientations of the d-orbital system. Note: in ionization of transition metals, the 1st and 2nd ionizations occur at the ns valence level, n = the principle energy level. If a 3rd ionization is needed, then an electron is oxidized from the (n-1)d-orbital.
- How to write electron configuration summaries of electronic orbital systems for cations, anions and neutral elements from the elements position on the periodic table. (reference => Aufbau Principle, Aufbau Diagram & Hund's Rule).