Paramagnetic and diamagnetic materials do not act as permanent magnets. Materials in which all of the electrons are paired are diamagnetic and weakly repel a magnetic field. Unlike oxygen, the apparent weight of most molecules decreases slightly in the presence of an inhomogeneous magnetic field. The Lewis structure model does not predict the presence of these two unpaired electrons. A Gouy balance compares the mass of a sample in the presence of a magnetic field with the mass with the electromagnet turned off to determine the number of unpaired electrons in a sample.Įxperiments show that each O 2 molecule has two unpaired electrons. We can calculate the number of unpaired electrons based on the increase in weight.

When we compare the weight of a sample to the weight measured in a magnetic field ( Figure 1), paramagnetic samples that are attracted to the magnet will appear heavier because of the force exerted by the magnetic field. Magnetic susceptibility measures the force experienced by a substance in a magnetic field. We need molecular orbital theory to explain this discrepancy. This paramagnetic behavior indicates that there are unpaired electrons in O 2, yet the Lewis structure does not indicate any unpaired electrons. The O 2(ℓ), however, collects in the magnetic field until it vaporizes. In this movie you can see that the N 2(ℓ) is not attracted to the horseshoe magnet and is therefore classified as diamagnetic. The following demonstration shows the difference between liquid N 2 and liquid O 2 when exposed to a magnetic field.Įxplanation. Demonstration: Liquid oxygen is attracted to a magnetic field

Orbitron gallery atomic orbitals