Paramagnetism
Definition and meaning of Paramagnetism in chemistry.
Paramagnetism is a form of magnetism where certain materials are weakly attracted by an externally applied magnetic field and form internal, induced magnetic fields in the direction of the applied magnetic field. It arises from the presence of one or more unpaired electrons in the atoms or molecules of the substance.
In more detail
Each unpaired electron has a magnetic dipole moment due to its spin. In the absence of an external magnetic field, these moments are randomly oriented, resulting in no net magnetization. When an external field is applied, the magnetic moments align partially with the field, creating a weak net attraction. This effect is temperature dependent, as thermal agitation opposes the alignment according to Curie's law. Materials that exhibit this property are useful in various analytical techniques like electron paramagnetic resonance spectroscopy.
Key facts
| Field | Physical Chemistry |
|---|---|
| Cause | Unpaired electrons |
| Temperature Effect | Decreases at higher temperatures |
Liquid oxygen (O2) is paramagnetic due to its two unpaired electrons and will be visibly attracted to the poles of a strong magnet.
Frequently asked questions
How can you predict if a molecule is paramagnetic?
By drawing its molecular orbital diagram or electron configuration; if there are unpaired electrons, it is paramagnetic.
Is paramagnetism a permanent effect?
No, the magnetic alignment disappears once the external magnetic field is removed.