1. The problem statement, all variables and given/known data Predict the number of unpaired electrons [Cr(H2O)6]3+ 2. Relevant equations 3. The attempt at a solution I under stand how to fill out the MO with the eg and t2g and all but I'm confused about determining the number of electrons. The answers state this is an octahedral d3 but I don't know why it is d3 Cr is the 4th element in the d block so it should be d4 but since it has a charge of +3 / is missing 3 electrons it should be d1 but neither of these are correct.