Question

Explain:

i. Paramagnetism

ii. Diamagnetism

iii. Ferromagnetism

OR

Explain the following with suitable examples:

i. Paramagnetism

ii. Diamagnetism

iii. Ferromagnetism

Answer 1

i. Paramagnetism:

a. The substances which have permanent magnetic dipoles and are attracted by the magnetic field are known as paramagnetic substances. The property thus exhibited is called paramagnetism.

b. Paramagnetic substances contain unpaired electrons. In such cases, the magnetic moments of electrons do not cancel each other.

c. Thus, paramagnetic substances have a net magnetic moment associated with them. When placed in a magnetic field, they experience net force of attraction.

d. Paramagnetic substances with greater number of unpaired electrons experience stronger pull in the magnetic field. Hence, as the number of unpaired electrons increases, the degree of paramagnetism increases.

eg. Oxygen, Cu²⁺, Fe³⁺, Cr³⁺ ions, etc.

ii. Diamagnetism:

a. The substances which are weakly repelled by the magnetic field are known as diamagnetic substances. The property thus exhibited is called diamagnetism. 

b. In diamagnetic substances, all electrons are paired. Each orbital contains two electrons having opposite spins. Thus, the spins are paired. Such substances are weakly repelled by the magnetic field.

eg. Water, sodium chloride, benzene, etc.

iii. Ferromagnetism:

a. The substances which are strongly attracted by the magnetic field and show permanent magnetism even when the magnetic field is removed are known as ferromagnetic substances. The property thus exhibited is called ferromagnetism. 

b. Ferromagnetic substances contain a large number of unpaired electrons. They can be permanently magnetised. They posses very strong magnetic property. 

eg. Iron, cobalt, nickel, CrO2, etc. 

The electronic configuration of iron (atomic number 26) is [Ar] 3d⁶ 4s². It contains four unpaired electrons. Hence, it is strongly ferromagnetic.