For the element it is better to have 3d5 4s1, becasue if it was 4s2 it would have a higher energy due to pairing up the 2 electrons in the 4s orbital, and also, the half filled d orbital is favourable. For the ion you have to move the 4s electron into the 3d, then take 3 away to get the 3+ charge, hence why it is 3d3. Hope this helps xx