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
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