How to find the spin number of a molecule like water

[TheCanadian]

How does one go about finding the spin number for a molecule like water for example? Do we consider the spin of the nuclei (e.g. proton, neutrons), and also look at which electrons are shared and not?

 

[DrClaude]

One usually considers only the total spin of the electrons, which is what is relevant spectroscopically. The spin of the nuclei might be relevant in some cases, but I have never seen the total spin of a molecule, or an atom for that matter.

The spin of the individual protons and neutrons is not relevant,only the total spin of the nuclei.

 

[TheCanadian]

One usually considers only the total spin of the electrons, which is what is relevant spectroscopically. The spin of the nuclei might be relevant in some cases, but I have never seen the total spin of a molecule, or an atom for that matter.

The spin of the individual protons and neutrons is not relevant,only the total spin of the nuclei.

Oh really? So if considering MRI for example, doesn't the energy of molecules in the person's body depend on the entire spin of the molecule under influence from the magnetic field?

 

[DrClaude]

Oh really? So if considering MRI for example, doesn't the energy of molecules in the person's body depend on the entire spin of the molecule under influence from the magnetic field?

No, MRI probes individual nuclear spins.