There are various substances which show magnetic behaviour. We have substances that are attracted by the magnetic field and are called paramagnetic. This phenomenon is called paramagnetism. Paramagnetic property is only shown when the substance contains one or more unpaired electrons. When a substance acquires a permanent magnetic moment, it is known as ferromagnetic and the phenomenon is called ferromagnetism. On the other hand, we also have substances which are repelled by the magnetic field and are called diamagnetic substances. A substance shows diamagnetism when it contains only paired electrons.
Most of the transition elements show paramagnetic behaviour. The unpaired electrons in (n-1) d orbitals are responsible for the magnetic properties. The paramagnetic character of the transition metals increases on moving from left to right as the number of unpaired electrons increases from one to five. The middle elements are found to possess the maximum paramagnetic property. The magnetic properties decrease with the decrease in the number of unpaired electrons. The transition metals which contain paired electrons depict diamagnetic behaviour.
Explanation for magnetic properties
An electron is a charged particle (negatively charged) which revolves around the nucleus and spins on its own axis. A magnetic field is generated due to the orbital motion and spin of the electron. The spinning of an electron in an orbit is very much similar to the flow of electric current in a closed circuit. Therefore, an unpaired electron is regarded as a micro magnet which has a definite magnetic moment. A substance which contains an unpaired electron when placed in a magnetic field interacts with the applied field. Consequently, an attractive force is exerted and the paramagnetic property is shown. The number of unpaired electrons determines the magnitude of the magnetic moment. The higher the number of unpaired electrons, the more the magnetic moment and the greater will be the paramagnetic behaviour of the substance.
In the case of paired electrons, the electrons in each pair will have an opposite spin. The magnetic field created by the electrons of the same pair is equal and opposite in nature. Hence, the magnetic field which is created by one electron is cancelled by the other. So the net effect of the magnetic moment is zero. These kinds of substances show diamagnetic properties and are repelled by the applied magnetic field.
So far we have seen the basic magnetic properties and the reason for this behaviour. If you have any query on this topic then you can download BYJU’S – The learning app for more information and other interesting content.