Diamagnetism
Definition and meaning of Diamagnetism in chemistry.
Diamagnetism is a physical property of matter that causes a substance to be weakly repelled by magnets. When we apply an external magnetic field, the material creates its own tiny opposing magnetic field. This induced field pushes away from the outside magnet rather than pulling toward it.
In more detail
To understand diamagnetism, we have to look closely at the electrons orbiting inside atoms. Electrons normally travel together in pairs within their specific chemical shells or orbitals. Each electron acts exactly like a tiny spinning magnet with its own magnetic field.
When two electrons pair up, their individual magnetic fields spin in opposite directions. These opposite spins cancel each other out to leave the atom with zero permanent magnetism. However, bringing a strong outside magnet near the paired electrons changes their normal flight path.
The outside field slightly alters the orbital motion of every electron cloud inside the material. This altered motion forces the electrons to generate a very weak new magnetic field. This newly induced magnetic field always points in the exact opposite direction.
According to a physics principle called Lenz's law, this new field fights the outside magnet. This gentle fighting force creates a weak physical repulsion that pushes the entire material away. Every single atom in the universe has paired electrons that create this diamagnetic repelling effect.
We just cannot always notice it because other types of magnetic forces are much stronger. For instance, unpaired electrons create a strong pulling force that easily overpowers this weak repulsion.
Key facts
| Field | Physical Chemistry |
|---|---|
| Magnetic interaction | Weakly repelled by external magnetic fields |
| Electron requirement | Requires all electrons to be paired |
| Origin effect | Induced orbital currents oppose the applied field |
| Common examples | Water, noble gases, and pure copper |
Liquid water gives us a perfect everyday example of a completely diamagnetic substance. Every single electron inside a water molecule pairs up neatly with another electron. Because it has no unpaired electrons, water always pushes away from outside magnetic fields. If you hold an incredibly powerful magnet near a dripping faucet, the water stream will bend away. Scientists have even used this weak repelling force to levitate small live frogs inside massive magnetic chambers.
Frequently asked questions
Is every single substance diamagnetic?
Yes, every atom has paired electrons that create a weak diamagnetic repelling force. However, if a substance also has unpaired electrons, their strong attractive pull hides the diamagnetism.
Does diamagnetism change when a substance gets hot or cold?
Unlike other magnetic properties, diamagnetism stays practically identical regardless of the surrounding temperature. The paired electrons remain securely trapped in their orbitals even when the material gets very hot.
How strong is the diamagnetic repelling force?
The repelling force is incredibly weak compared to the pull of normal refrigerator magnets. You usually need specialized lab equipment or huge electromagnets to actually see this tiny repelling effect.