10.2.7 CIA Demonstration: The Paramagnetism of Oxygen

Question 1

CIA Demonstration: The Paramagnetism of Oxygen

Answer 1

• Molecular orbital theory (MO theory) predicts the paramagnetism of oxygen due to unpaired electrons.
• Valence bond theory has been superceded by molecular orbital theory since MO theory more closely describes what is observed

Question 2

note

Answer 2

• Bolts are aligned on a horseshoe magnet so that the space is small enough to trap a pouring liquid. The poles of the magnet are between the bolts.
• No liquid nitrogen is caught and suspended between the poles of a strong horseshoe magnet. This is expected since liquid nitrogen is diamagnetic.
• A small amount of liquid oxygen is caught and suspended between the poles of a strong horseshoe magnet. It will hang there for a while and then evaporate. This is expected since liquid oxygen is paramagnetic.
• Both valence bond theory and molecular orbital theory predict that dinitrogen is diamagnetic (has no unpaired electrons) and will not be attracted to the poles.
• Molecular orbital theory predicts that oxygen is paramagnetic due to its two unpaired electrons.
• Valence bond theory does not make that prediction.
• When a theory doesn’t make the correct prediction, it is superceded by a superior theory; one that does explain an experimental observation.