Cr 1s2 2s2 2p6 3s2 3p6 4s1 3d5
Mn 1s 22s 22p 63s 23p64s 23d5
Fe 1s 22s 22p 63s 23p64s 23d6
Ca 1s 22s 22p 63s 23p64s 2
Ni1s 22s 22p 63s 23p64s 23d8