Why Ni⁺² paramagnetic whereas Zn⁺² diamagnetic?

 

Para magnetism and diamagnetism of a substance depends on the number of electrons occupied by it. A paramagnetic substance is one that contains one or more unpaired electrons.

On the other hand, a diamagnetism substance is one that does not contain any odd electrons. Now, Ni ⁺² ion is 3d⁸ system. According to Hund’s rule the outer electronic configuration of Ni⁺² ions is [Ar] 3d⁸. 

From electronic configuration of Ni ⁺² ion, it has been found that it has two unpaired electrons.

Now, depending upon the hybridization, there are two types of possible structure of Ni ⁺² ion are formed with co-ordination number 4.

If the complex involves ‘sp3’ hybridization, it would have tetrahedral structure. Again, if the complex involves ‘dsp2’ hybridization, it would have squareplanar structure.

Consequently, for the formation of tetrahedral structure through the ‘sp3’ hybridization, the 3d-orbital of nickel atom remain unaffected.

Therefore, 3d-orbital of Ni ⁺² ion possessed two unpaired electrons and hence the concern complex would be paramagnetic.

For example, in case of [NiCl4] ^2– complex ion, Ni⁺² ions with co-ordination 4 involves ‘sp3’ hybridization. Hence the geometry of, [NiCl4] ^2– complex ion would be tetrahedral.

Under this condition, the electronic arrangement of Ni ⁺² ion is evidently shown that the 3d-orbitals of Ni ⁺² ion have two unpaired electrons and hence Ni⁺² ion is paramagnetic.

On the other hand the atomic number of zinc is 30. According to Hund’s rule the outer electronic configuration of Zn⁺² ions is [Ar] 3d¹⁰ that is Zn⁺² ions is 3d¹⁰ system.

That is, 3d orbital of Zn⁺² ions is completely fulfilled but outer 4s orbital is vacant.

Hence according to valence bond theory the outer ‘4s’ orbital of Zn⁺² ion is  combined with the vacant three 4p orbital and form energetically equivalent four sp3 hybridized orbitals.

Now, four similar or dissimilar ligands are attached with these four hybridized orbitals through the formation of four co-ordinate bond.

As a result, Zn⁺² ion forms tetrahedral molecule involving ‘sp3’ hybridization.

 

For example, in case of [Zn(NH3)4]⁺² complex ion, Zn⁺² ions with co-ordination 4 involves ‘sp3’ hybridization. Hence the geometry of, [Zn(NH3)4]⁺² complex ion would be tetrahedral.

The outer electronic configuration of Zn⁺² ions and its hybridization are shown below.

From the above electronic configuration of Zn⁺² ions, it has been found that the number of unpaired electrons is zero. Since the Zn⁺² ion has no unpaired electrons, hence it is diamagnetic.

• Why Ni⁺² paramagnetic whereas Zn⁺² diamagnetic?
• Why is Ni⁺² ion paramagnetic in nature?
• Why is Zn⁺² ion diamagnetic in nature?
• Why Zn⁺² diamagnetic whereas Ni⁺² paramagnetic?

 

 Ni⁺² paramagnetic whereas Zn⁺² diamagnetic, Zn⁺² diamagnetic whereas Ni⁺² paramagnetic, Ni⁺² ion paramagnetic in nature, Zn⁺² ion diamagnetic in nature,

Read more : Dehydrogenations of alcohol reactions