Oxidation States and Inert Pair Effect

The inert pair effect refers to the valence s- electrons of a high-atomic-number atom’s reluctance to participate in chemical processes due to poor shielding of these electrons by inner orbital electrons. As a result, the s-electrons are unavailable for bond formation. If we move along the group, this effect becomes stronger. Due to the inert pair effect oxidation state of bigger elements drops, and smaller elements’ stability improves. But, what all takes place during the inert pair effect and what can be defined as the oxidation states? This article will explain oxidation states, inert pair effect, and inert pair effect meaning. 

What is the oxidation state? 

Oxidation states can be defined as the degree of oxidation for any atom in a chemical compound. It can also be inferred as a hypothetical charge that an atom would have if all atoms of different elements were ionic. Oxidation states can be represented by positive, negative or zero integers. An element’s typical oxidation state is drawn as a fraction in some unusual cases. For example, such as Fe3O4 magnetite, the value of iron is written as 8/3.  

The increased comprehended oxidation state is +8 for ruthenium, xenon, osmium, iridium, hassium, and several plutonium complexes. Also, the lowest known oxidation state is -4 for different carbon group elements.

Oxidation is the loss of electrons due to a rise in an atom’s oxidation state in a chemical effect. The deduction can also be the increase of electrons due to a lessening oxidation state in a chemical equation.

Oxidation states different rules to be followed: 

• A free element which is an uncombined element, possesses no oxidation state

• Whereas the oxidation state of an easy (monoatomic) ion will be comparable to the ion’s net charge. For instance, The oxidation state of Cl – is -1.

• The hydrogen oxidation state of +1 is correlated to oxygen, whose oxidation state is -2. Hydrogen has an oxidation value of +1 static metal hydrides (such as LiH), peroxides have an oxidation state of -1 (such as HO2), and superoxides have an oxidation state of -½ (such as KO).

• The algebraic aggregate of oxidation states for all atoms should be zero in an impartial molecule. Whereas, in ions, the amount of atoms of the oxidation states is analogous to the charge of the ion. 

How to indicate oxidation states? 

The oxidation state of different elements in the periodic table can be defined by their group number. From the table, we can tell that boron, which is a group III element, typically possesses an oxidation state of +3, and nitrogen, which is a group V particle, has an oxidation state of -3.  

But one thing to keep in mind is that oxidation state changes and is not dependent on the group number. This method can also be utilised as a common guideline or rule. For instance, transition components differ and possess various sorts of oxidation states which are not conditional on groups. 

For instance, the cumulative charge of a sulfite ion SO32- is 2-, so each oxygen atom is inferred to be in the ordinary oxidation state of -2. But, because sulfite has three oxygen atoms, it will give 3x 2 = – 6 to the total charge. So we can tell that sulfite has +4 as its oxidation state, and the charge on it will be 2-: (+4-6 = -2). 

What is the inert pair effect? 

The Inert Pair Effect can be defined as a negligible effect on any element’s properties. However, this effect has a more impact on the element and can also affect the periodic trends. Mainly the transition elements of the periodic table show this effect. Transition elements have s-orbital as their outermost electrons, which tend to remain outside the chemical process. 

Definition – When the electrons in a valence shell of s-orbital cannot ionise, it is termed an inert pair effect. Or you can say non-participation of valence shells that have s-orbital electrons. 

What are the limitations of the inert pair effect? 

The inert pair theory possesses some limitations. Suppose we explain this in terms of electrons, or in other words, their expected high ionisation enthalpy value. Let’s take an example of group 13 elements and know exactly what the limitations are.

In this ionisation, enthalpy will decrease as well as move from up and down. This table shows a few anomalies—an increase in ionisation enthalpy from Al to Ga and indium to thallium.   

The inert pair effect that Sidgwick proposed cannot account for this information. Their simple explanation can be that d-block contraction affects Ga’s ionisation enthalpy. Tl’s comparatively high ionisation is due to relativistic effects due to poor shielding of the d- and f- orbitals. 

Uses of inert pair effect

The high stability of low oxidation states of heavy p block elements can be explained through the inert pair effect.  

The inert pair effect also describes the increase in ionisation values of s-orbital electrons in p-orbital elements.  This technique also explains Tl+3’s highly oxidative nature and strong reactivity.  

It also explains the anomaly in the melting and boiling points of elements. 

Conclusion

you can read about oxidation and inert pair effects by solving oxidation states and inert pair effect questions. The inert pair effect occurs in heavier elements of groups 13,14,15, and 16 in the periodic table. It also describes the increase in stability of oxidation states with two fewer electrons to complete the group valency.