Answer
Chromium (Cr): 6 unpaired electrons
Copper (Cu): 1 unpaired electron
Work Step by Step
The two exceptions to the filling order in the periodic table occur in the transition metals. The first exception is chromium (Cr), and the second exception is copper (Cu).
For chromium (Cr), the atomic orbital diagram is as follows:
1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^5
There are 6 unpaired electrons.
For copper (Cu), the atomic orbital diagram is as follows:
1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^10
There is 1 unpaired electron.
