Question

Explain the following with suitable examples:
(i) Ferromagnetism
(ii) Paramagnetism
(iii) Ferrimagnetism
(iv) Antiferromagnetism

Answer 1

As we know that, the magnetism of any compound or element or ion is because of magnetic moments which arise due to, they contain electrons and each electron itself acts as a tiny magnet. The reason for the magnetic behaviour, Ferromagnetism, Ferrimagnetism and Antiferromagnetism is due to the grouping metal ions in small regions.

The magnetic properties of elements, compounds or ions are due their magnetic moments which arise due to the orbital motion and spinning motion of electrons. The orbital motion arises when electrons move around the nucleus and spinning motion arises when electrons move around its axis.

Complete step by step solution
(i) Ferromagnetism:- Substances that are strongly attracted by a magnetic field show permanent magnetism. These substances have properties that they can also show magnetic behaviour without the external magnetic field such substances are Called ferromagnetic substances. The reason for such magnetic behaviour by these substances is that in the solid state, the metal ions of these substances arrange themselves in a group that is called a domain. Each domain itself produces a magnetic field of its own. When the substances like iron, nickel, cobalt, gadolinium, chromium dioxide are placed in a magnetic field all the domains get oriented in the direction of the magnetic field. As a result, the substance has a very high magnetic moment.

(ii) Paramagnetism:- As we already know, that para term is used for unpaired electrons. therefore, the substances which contain unpaired electrons are attracted by the external magnetic field are called paramagnetic substances such as ${{\rm{O}}_{\rm{2}}}$, ${\rm{C}}{{\rm{u}}^{{\rm{2 + }}}}$etc. However, these substances lose their magnetism in the absence of magnetic fields.

(iii) Ferrimagnetism:- The substances which are arranged themselves in a domain and these domains are in the opposite direction but not in equal number. Therefore, these substances produce some net magnetic moment such as magnetite(${\rm{F}}{{\rm{e}}_{\rm{3}}}{{\rm{O}}_{\rm{4}}}$) and ferrite of the formula${{\rm{M}}^{{\rm{2 + }}}}{\rm{F}}{{\rm{e}}_{\rm{2}}}{{\rm{O}}_{\rm{4}}}$where ${\rm{M}} = {\rm{Mg,}}\;{\rm{Cu,}}\;{\rm{Zn}}$ etc.

(iv) Anti-ferromagnetism:- As the name indicated anti meaning opposite arrangements, so due to presence of equal number of magnetic moments in opposite direction, the net magnetic moment of substances is zero such as ${\rm{MnO}}$.

Note:
Ferromagnetic and antiferromagnetic solids change into paramagnetic at high temperatures. Also, each ferromagnetic substance has a characteristic temperature above which no ferromagnetism is observed is known as curie temperature.