Is the following ion diamagnetic or paramagnetic?
We are being asked if the species is paramagnetic or diamagnetic so we have to determine the electron configuration of Cr3+ ion.
Recall that paramagnetic species have 1 or more unpaired electrons while diamagnetic contains 0 unpaired electrons.
To figure that out, let’s first write the electron configuration of a neutral (uncharged) Cr atom.
Ground-state means that Chromium is in its lowest energy form (not in an excited state).
Neutral element: Atomic number = # protons = # of electrons
Neutral Chromium (Cr):
• Atomic number = 24
• # of electrons = 24 e-