Question

Which ions are paramagnetic and which ions are diamagnetic. Please explain why each ion is either paramagnetic or diamagnetic.

Answer 1

magnetic behaviour of ions is determined by drawing their MO diagram..in that if there are unpaird electrons in anti bonding MOs then the ion is para magnetic whether positiv or negative...if paird electrons are present in anti bonding MOs then ion is diamagnetic..

Since paramagnetic has an unpaired electron, it is always alone ! But diamagnetic means every electron is paired together so they always have friends ! lol, I know it's ridiculous, but I got through college with half the funny things they've told us.

Diamagnetic has no unpaired e-, while paramagnetic does.
Add up the amount bonding valence electrons it has. (make sure to take into account the charge) Then slowly fill in the orbitals and check if the end result has unpaired electrons.

ex. Cr 3+: normally it would have 4 valence e-, but due to the charge, it lost 3 and has only 1 left. This electron sits in the 3d orbital alone, thus making it paramagnetic.