how many unpaired electrons in cr|Electron Configuration for Chromium (Cr, Cr2+, Cr3+) : iloilo 1s2 2s2 2p6 3s2 3p6 3d5 4s1. For the Cr 2+ ion we remove one electron from 4s1 and one from the 3d5 leaving us with: 1s 2 2s 2 2p 6 3s 2 3p 6 3d 4. For the Cr 3+ ion we remove a total of three electrons (one from the 4s1 and two from the 3d5) leaving us with. 1s 2 2s .