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Difference Between Valency and Oxidation Number for JEE Main 2024

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Last updated date: 13th Jul 2024
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Valency and Oxidation Number: Introduction

Atoms from various elements are used to create all compounds. Depending on how many open orbitals are accessible to them or how many electrons a specific atom may release, these atoms are mixed in various ratios. Two concepts are used to describe the causes of these various atom arrangements: valency and oxidation number. Valency and oxidation number differ primarily in that valency refers to the number of electrons in an atom's outermost shell whereas oxidation state refers to the number of electrons an element in a particular compound has gained or lost.


Category:

JEE Main Difference Between

Content-Type:

Text, Images, Videos and PDF

Exam:

JEE Main

Topic Name:

Difference Between Valency and Oxidation Number

Academic Session:

2024

Medium:

English Medium

Subject:

Chemistry

Available Material:

Chapter-wise Difference Between Topics


What is Oxidation Number?

The charge of the main atom in a coordination molecule, if all the bonds surrounding it were ionic bonds, is known as the oxidation number. In practically all cases, transition metal atoms make up the bulk of coordination complexes. Chemical compounds known as ligands encircle this metal atom. 


To establish coordination bonds with metal atoms, these ligands can share their lone electron pairs with them. It resembles a covalent bond once the coordination bond has formed. This is because, similar to a covalent link, the two atoms in a coordination bond share a pair of electrons. However, the coordination bonds are treated as ionic bonds for calculating the central metal atom's oxidation number.


The metal atom's orbitals must be vacant for coordination bonds to form. The majority of the d orbitals in transition metals are vacant. They can therefore serve as the main metal atom in coordination complexes. Roman numbers are used to signify the central atom's oxidation number. The Roman number, enclosed in brackets, indicates the charge of the primary atom. If a hypothetical metal atom "M" has an oxidation number of 3, for instance, the oxidation number is expressed as M(III).


Find the Oxidation Number of an Atom:

The number of electrons an atom or ion has either gained or lost in comparison to the neutral atom is known as the oxidation number or state of the atom or ion. The number of electrons lost by each electropositive metal atom in groups 1, 2, and 3 is fixed, and their positive oxidation numbers are always positive.


More electronegative atoms in molecules receive electrons from less electronegative atoms, resulting in negative oxidation states. The number of electrons lost or acquired determines the oxidation state's numerical value.


An atom or ion in a molecule or ion's oxidation number or oxidation state is determined by:


  • Compiling the constant oxidation states of all the atoms, molecules, and ions linked to it.

  • Comparing the total charge of a molecule or an ion to its total oxidation state.


What is Valency?

The maximum number of electrons that an atom can gain, share, or lose before stabilizing is known as valency. The octet rule specifies the most stable form of an atom for both metals and nonmetals. It claims that a configuration is stable if an atom's outermost shell is filled with eight electrons. 


In other words, it is stable if the s and p sub-orbitals are filled with ns2np6. This arrangement of electrons naturally exists in noble gas atoms. Therefore, for additional elements to follow the octet rule, they must either gain, lose, or share electrons. The valency of that atom refers to the maximal number of electrons engaged in this stabilization process.


As an illustration, the electron configuration for the element silicon is 1s22s22p63s23p2. n = 3 for the outermost shell. That shell contains four electrons. To complete the octet, it must therefore acquire 4 extra electrons. To complete the octet, silicon typically needs to share 4 electrons with other elements.


Find the Valency of an Atom:

As is knowledge, magnesium has two electrons in its outermost shell compared to one for hydrogen. Since hydrogen is easily capable of losing one electron and becoming stable, its valency is 1. Magnesium, on the other hand, has a value of 2 since it can lose 2 electrons with ease and also achieve stability.


Additionally, it is not just based on the loss of an electron by an atom. For instance, the outermost orbital of fluorine has 7 electrons. Since losing 7 electrons is difficult, it gains 1 electron to finish out its octet. It acquires 1 electron, making its valency 1. The elements in the same group of the periodic table have the same valency.


For example, all of the elements in group 8 have 8 electrons and filled orbitals, hence all of the elements in this group have zero valencies.


Difference Between Valency and Oxidation Number:

The valence electrons of an atom are associated with the concepts of oxidation number and valency. The main difference between valency and oxidation number is that the former refers to the maximum number of electrons an atom can lose, gain, or share to stay stable. In contrast, the latter refers to the number of electrons an atom can gain or lose to establish a bond with another atom. Furthermore, the phrase "valency" refers to any chemical element, but the term "oxidation number" refers primarily to coordination complexes. Lets now differentiate between valency and oxidation  number:


S.no. 

Parameter 

Valency 

Oxidation Number


Definition 

Valency is the maximum number of electrons an atom loses, gains, or shares to become stable. 

Valency is the maximum number of electrons an atom loses, gains, or shares to form a bond with another atom. 


Application 

Applied for any chemical element. 

Applied regarding coordination complexes. 


Calculation 

Determined using the electron configuration of a chemical element. 

Determined considering the ligands and the overall charge of the coordination complex. 


Representation 

As a numerical value. 

Given in Roman numbers inside brackets. 


Summary

Valency and oxidation number are two terms that are often confused, but they have different meanings. Valency is the number of electrons that an atom can lose, gain, or share to form a chemical bond. Oxidation number is the charge that an atom would have if all of its bonds were ionic. The main difference between valency and oxidation number is that valency is a property of an individual atom, while oxidation number can vary depending on the molecule or ion that the atom is a part of. In general, valency is a more fundamental property than oxidation number, and it is often used to predict the types of chemical bonds that an atom can form. Oxidation number, on the other hand, is a more useful concept for understanding the reactivity of molecules and ions.

FAQs on Difference Between Valency and Oxidation Number for JEE Main 2024

1. What is valency?

The amount of hydrogen atoms that can directly or indirectly mix with or replace one of an element's atoms is known as the valence of the element. For instance, oxygen possesses two valence electrons despite having six valence electrons. While certain elements might have multiple power combinations (or valences), others might only have one.

2. What is oxidation number?

The charge that an atom seems to have when forming ionic connections with other heteroatoms is used to define an atom's oxidation number. Even if it forms a covalent bond, an atom with a higher electronegativity is given a negative oxidation state.


An atom is given an oxidation state according to the definition if:


  • bonds made up of heteroatoms.

  • Regardless of the type of bonding, ionic bonds are always created by either obtaining or losing electrons.

3. Differentiate between valency and oxidation number.

The main difference between valency and oxidation number is that while oxidation number refers to the number of electrons an atom can lose or gain to establish a bond with another atom, valency refers to the maximum number of electrons an atom can lose, gain, or share to become stable.


The valence electrons of an atom are associated with the concepts of oxidation number and valency. The electrons that are located in an atom's outermost orbitals are known as valence electrons. Because of the weak attraction of these electrons to the atomic nucleus, atoms can easily remove or share them with other atoms. An atom's oxidation number and valency are determined by the loss, gain, or sharing of electrons, which ultimately results in the formation of a chemical bond between the two.

4. How is valency calculated?

When the number of electrons in the outer shell is four or less, the valence of an atom is equal to that number. The outer shell's valence is then equal to eight less the amount of electrons. You can quickly compute the valence if you know how many electrons there are.

5. State the importance of valency.

The significance of valence: Since the outer shells of the reacting atoms come into contact first, the outer shell electron is typically a participant in chemical reactions. In a chemical reaction, the atoms trade valence electrons to stabilize their valence shell.