Why Do Transition Elements Have Higher Oxidation States

Alternatively, the oxidation state of an element can be defined as the degree of an element’s ability to lose electrons from its valence shell in a chemical compound. This is also referred to as the degree of oxidation of the element in question. During the formation of their compounds, transition elements exhibit a wide range of oxidation states. Manganese, for example, exhibits a wide range of oxidation states in its various compounds, ranging from +2 to +7 in a range of oxidation states. Some of the elements, on the other hand, have only a few oxidation states. Zinc and scandium are two elements that are found in only a few different oxidation states compared to other elements. The fact that any of the elements has so few oxidation states is due to the fact that they have so few electrons to lose from their valence shells. For example, scandium has an excessive number of d electrons and, as a result, has a limited number of orbitals in which to share electrons with others, resulting in a very high valence. The variable oxidation states of valence electrons are caused by the extremely small number of electrons that are filled in the d-orbital in such a way that their oxidation states differ from one another by a unitary amount of energy.

Stability of oxidation state : 

Chromium, manganese, and cobalt exhibit extremely high levels of oxidation. Manganese does not exhibit a +7 oxidation state when present in halides, but the +7 oxidation state of manganese in the compound MnO₃F is known. Due to the fact that the ∆_hydH of Cu²⁺ is greater than that of Cu⁺, which compensates for the second ionisation enthalpy of the metal, it is known that Cu²⁺ (aq) is more stable than Cu⁺ (aq). The oxidation state of manganese in Mn₂O₇ is +7, demonstrating that the oxidation state of manganese is higher in manganese  oxides. The Mn oxide, Mn₂O₇, has a higher oxidation state than the Mn fluorides, MnF4, because oxygen has a tendency to form multiple bonds with metals, as opposed to the Mn fluorides, MnF₄. This bridge is included in Mn₂O₇, which has each Mn surrounded by four O’s in a tetrahedral fashion. The other elements in the compound, such as Fe₂O₃ and V₂O₄, have oxidation states of +3 and +4 respectively, as do the other elements in the compound. Because of the inert pair effect in the p-block elements, the heavier elements prefer a low oxidation state, whereas the d-block elements prefer a high oxidation state, which is the polar opposite of the p-block elements. Similar to the findings in group 6, Mo (VI) is found to have greater stability when compared to Cr (VI).

Inert pair effect : 

It is the tendency of the outermost atomic s-orbital electrons to stay unshared in compounds of post-transition metals, which is known as the inert-pair effect For the heavier elements in groups 13, 14, 15, and 16, the term “inert-pair effect” is frequently used to describe the growing stability of oxidation states two less than the group valency. Nevil Sidgwick coined the phrase “inert pair” in 1927. s electron pairs are more closely bonded to the nucleus in these atoms, which makes them more difficult to ionise or share.

It is not possible to shelter the s-electrons of the valence shell from the d- (and f-) orbitals that occur before them in the 4th, 5th, and 6th periods of the periodic table. A less active role in bond formation is played by the inert pair of ns electrons because the nucleus is able to hold them more securely.

Conclusion : 

Alternatively, the oxidation state of an element can be defined as the degree of an element’s ability to lose electrons from its valence shell in a chemical compound. This is also referred to as the degree of oxidation of the element in question. It is the tendency of the outermost atomic s-orbital electrons to stay unshared in compounds of post-transition metals, which is known as the inert-pair effect For the heavier elements in groups 13, 14, 15, and 16, the term “inert-pair effect” is frequently used to describe the growing stability of oxidation states two less than the group valency. Nevil Sidgwick coined the phrase “inert pair” in 1927.