CBSE Class 12 Chemistry Notes: Solid States – Magnetic properties of solids

Magnetic properties of solids:-

• The magnetic properties of materials are studied interms of magnetic moment and they are generated due to orbital and spinning motion of electrons.
• Electron is a charged particles thus its orbitals motion produces a small magnetic field along the axis and it also have magnetic moment due to its spin angular momentum.
  

Due to difference in magnetism magnetic substances are divided in following categories:-

1. Diamagnetic substances:-
Substances which are weakly repelled by the external magnetic field are called the diamagnetic substances and the magnetism is called diamagnetism. This property is shown only by substances containing fully filled orbitals
Example:
TiO2, H2O, NaCl etc.

2. Ferromagnetic substances:-
Substances which show the permanent magnetic moment even in the absence of magnetic field are called ferromagnetic substances. They remains permanently magnetized due to the reason, the metal ion of these substances are group together to form domains and when magnetic field is applied these domains are oriented in the same directions. Thus when magnetic field is removed these domains remains permanently oriented and forms very strong permanent magnets
Example:
Fe, Ni, Co

3. Paramagnetic substances:-
Substances which are weakly effected by the external magnetic field are called the paramagnetic substances. Paramagnetism is shown by such substances whose atoms or ions have unpaired electrons.
Example:
O2, Cu+2, Fe+3.

4. Antiferro magnetic substances:-
Substance which are expected to possess paramagnetism or ferromagnetism on the basis of magnetic moments of the domains but actually they possess net o magnetic moment are called antiferro magnetic substances.
Example:
MnO

5. Ferromagnetic substances:-
Substances which are expected to possess large magnetism on basis of magnetic moments of domains but have small magnetic moment are called ferromagnetic substances.
Example:
Magnetic (Fe3C4)

6. Curie temperature:-
The temperature above which no. ferromagnetism of a ferromagnetic substance is observed is called as curie temperature.

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