Paramagnetism/Diamagnetism Predictions

[dissolver]

Is it impossible to use the Localized Electron Model to predict whether a given molecule is para/diamagnetic?

Since the LE model only allows for the prediction of where specific electron pairs are located, e.g. between which orbitals and belonging to which atoms in the molecule, and thus is impotent in predicting which specific orbitals are filled by the present electrons.

Also since LE doesn't consider MOs, it seems prediction of a molecule's magnetism is impossible?

Is my reasoning correct?

Also, my chem. text simply states that paramagnetism is associated with unpaired electrons in an orbital. So does this mean that all free radicals are paramagnetic?

 

[GCT]

Yes, it doesn't consider the molecular orbitals, and therefore is not useful in the determination whether a molecule is para or dia magnetic. This is a common assertion for the VSEPR model in chemistry texts.

I don't believe all radicals are paramagnetic, you'll really have to understand the molecular orbital diagram for a particular molecule to determine its magnetic character and there are quite a few ways of doing that. If there remains one electron that is unpaired in the non bonding molecular orbital, the removal of an electron would cause it to rather become diamagnetic. However, I'm going to need to investigate this matter more fully since it needs a more complete explanation.

 

[ravenprp]

Your reasoning is correct. The Localized Electron Model (LE) is not capable of predicting whether a molecule is paramagnetic or diamagnetic because it does not take into account the molecular orbitals (MOs) of the molecule. MOs are crucial in determining a molecule's magnetic properties as they describe the distribution of electrons throughout the molecule, including their spin. Therefore, without considering MOs, the LE model is unable to accurately predict a molecule's magnetism.

As for your question about free radicals, yes, all free radicals are paramagnetic because they contain unpaired electrons. This means that they have an overall magnetic moment and can be attracted to a magnetic field. However, not all paramagnetic molecules are free radicals. Molecules with at least one unpaired electron, such as oxygen and nitrogen, are also paramagnetic but are not considered free radicals.