Question

Explain Ferrocyanide ion is diamagnetic while Ferricyanide ion is Paramagnetic.

Answer 1

Hint : We know that diamagnetism is the phenomenon in which an atom contains paired electrons and paramagnetic is the phenomenon in which an atom contains unpaired electrons. The origin of magnetism is explained by taking into consideration the circular motion of electrons.

Complete Step By Step Answer:
Diamagnetic substances are magnetized weakly when placed in an external magnetic field in a direction that is opposite to the applied field. The type of magnetism that is exhibited by these substances is known as diamagnetism. Examples of diamagnetic substances are copper, gold, antimony, bismuth, silver, lead, silicon, mercury, etc. The electron's orbital motion gives rise to an orbital magnetic moment. In addition to this, the electrons tend to spin around their own axis, creating a spin magnetic moment. Electrons in an atom can have a clockwise or anticlockwise spin. In a similar way, the electrons can revolve around the nucleus in a clockwise or anticlockwise direction. Since there is no electron pair in Ferrocyanide $~\left( F{{e}^{+2}} \right)$ its diamagnetic as its $3{{d}^{6}}\text{ }4{{s}^{0}}.$
Substances that get magnetized weakly when placed in an external magnetic field in the same direction as the direction of the externally applied field are known as paramagnetic substances. These substances are different from ferromagnetic and diamagnetic substances. They have a tendency to move from the weaker to the stronger part of the magnetic field in a paramagnetic substance, each atom has a permanent magnetic dipole moment because of the way they spin, the magnetic moments are oriented. However, the direction of magnetic moments can have random orientations when there is thermal motion. Due to which the net magnetic moment of this substance is zero. Since there is one electron pair in Ferricyanide $~\left( F{{e}^{+3}} \right)$ its diamagnetic as its $3{{d}^{5}}\text{ }4{{s}^{0}}.$
Therefore, ferrocyanide is diamagnetic in nature while ferricyanide ion is paramagnetic.

Additional Information:
The electrons present inside the atoms move in circular orbits around the nucleus; this is similar to a circular coil carrying current. The electron's orbital motion gives rise to the orbital magnetic moment. The electrons tend to spin around in their own axis, thus creating a spin magnetic moment. The magnetic moment of an atom is the result of the vector sum of the orbital and spin magnetic moment as one electron is not paired, so ferricyanide is paramagnetic in nature.

Note :
Remember that it’s to be noted that there are two types of complexes in coordination compounds namely high spin complex and low spin complex. If the inner d orbital is used for the formation of compound then the compound is low spin complex and if the outer d orbital is used then the compound is high spin complex.