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What Is Difference Between Valency And Oxidation, Elements of the Periodic Table

Difference between Valency and Oxidation : Valency is defined as the number of valence electrons in a neutral atom, whereas oxidation number is defined as the oxidation state which is due to the electronegativity difference of that atom in the molecule (after gaining or losing an electron).
authorImageShrivastav 16 Oct, 2024
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Difference between Valency and Oxidation

Difference between Valency and Oxidation: Valency and oxidation are the topics of JEE Main 2025 Chemistry Syllabus . Valency is the number of Chemical bonds an atom can form. Oxidation is the number of elements in a chemical compound and is a measure of the degree of oxidation or reduction. Candidates can check the difference between Valency and Oxidation in the article below.

What is Valency?

The valency of an element is the number of chemical bonds an atom can form. It is also known as the combining capacity of an element. Valency is determined by the number of electrons an atom needs to gain, lose, or share to achieve a stable electron configuration, typically the configuration of noble gases.

The concept of valency is especially important in understanding how elements combine to form compounds. For example, sodium (Na) has a valency of +1 because it prefers to lose one electron to achieve a stable configuration, whereas chlorine (Cl) prefers to gain one electron. Sodium and chlorine can react to form NaCl (table salt), in which sodium donates an electron to chlorine.

It's important to note that valency is a simplified concept used to explain chemical bonding and is not always a fixed number for all compounds involving a particular element. The valency of an element can vary depending on the specific compound it forms.

Important Facts For Valency of an Element

Some of the major important facts regarding the valency of an element are given below.
  • The valency of an element is the number of electrons present in the outermost shell that can participate in a reaction.
  • It depends on the group number of an element. Such as elements from the group numbers 1, 2, 13 and 18, the valency is often equal to the group number. For example, elements in group 1 have a valency of 1 and group 2 have a valency of 2 and so on. However, 17 and 18 groups are exceptions.
  • The transition elements present in the periodic table can have variable valencies.
  • The electronic configuration of an element also determines its valency. Elements lose or gain free electrons to achieve the stable noble gas configuration.
  • Elements having 1, 2 and 3 electrons in their outermost shell donate their free electrons to achieve a noble gas electron configuration. They are generally metals.
  • Elements having 5, 6, and 7 elements in their outermost shell generally accept the free electrons from the neighbouring elements to achieve the noble gas configuration. They are generally non-metals.

What is the Oxidation Number?

The oxidation number of an element in a chemical compound is a measure of the degree of oxidation or reduction. The oxidation state is also referred to as the oxidation number. The degree of oxidation is calculated through the loss of electrons, and the degree of reduction is calculated through the gain of electrons.

It's important to note that the oxidation number is a formalism and doesn't necessarily represent the actual distribution of electrons in a molecule. It's a useful concept for balancing redox reactions and understanding the transfer of electrons between atoms. The sum of the oxidation numbers in a neutral compound is always zero, and in an ion, it equals the charge of the ion.

Important Facts for Oxidation Number

The oxidation number of an element is assigned based on certain rules:
  • Elemental form : An element's oxidation number is zero in its uncombined (elemental) state. The oxidation number of pure elemental oxygen (O2), for example, is zero.
  • Monatomic ions: The oxidation number of a monatomic ion equals the ion's charge. For example, sodium (Na+) has an oxidation number of one, and chloride (Cl-) has an oxidation number of one.
  • The sum of a compound's oxidation numbers is: The sum of the oxidation numbers of all the atoms in a neutral compound is zero. The sum of the oxidation numbers in an ion equals the ion's charge.
  • Hydrogen has an oxidation number of +1 in the majority of compounds. Hydrogen, on the other hand, has an oxidation number of -1 in hydrides like NaH.
  • Oxygen: The oxidation number of oxygen in most compounds is -2. There are some exceptions, such as peroxides (for example, H2O2), in which each oxygen has an oxidation number of -1.
  • Fluorine has an oxidation number of -1 in all compounds.

Difference between Valency and Oxidation Number

Some major difference between valency and oxidation numbers is given in the table below.
Difference between Valency vs. oxidation Number of an element

Valency

Oxidation Number

The Valency is the number of electrons present in the outermost shell of a particular element The oxidation number is the number of electrons that a particular atom can lose, gain, or share with another atom.
Does not indicate the electric charge of an atom in a compound. Indicates the electrical charge of an atom in a compound.
Determines the maximum number of bonds that an atom can have. Does not indicate the number of bonds that a particular atom can have
The valency of a pure element depends on the number of electrons it has in its outermost shell of an atom. The oxidation state of a pure element is always zero.
The valency of an element is always in whole numbers. The oxidation state of an element can be negative as well as positive, and can also have a fractional value.

Valency of the First 30 Elements of the Periodic Table

The Valency of an element is the number of outermost electrons present in the atom. Check the valency of the first 30 elements of the periodic table here.
Difference Between Valency and Oxidation Number

Element

Atomic Number

Valency

Hydrogen 1 1
Helium 2 0
Lithium 3 1
Beryllium 4 2
Boron 5 3
Carbon 6 4
Nitrogen 7 3
Oxygen 8 2
Fluorine 9 1
Neon 10 0
Sodium (Na) 11 1
Magnesium (Mg) 12 2
Aluminium 13 3
Silicon 14 4
Phosphorus 15 3
Sulfur 16 2
Chlorine 17 1
Argon 18 0
Potassium (K) 19 1
Calcium 20 2
Scandium 21 3
Titanium 22 4
Vanadium 23 5, 4
Chromium 24 2
Manganese 25 7, 4, 2
Iron (Fe) 26 2, 3
Nickel 27 3, 2
Cobalt 28 2
Copper (Cu) 29 2, 1
Zinc 30 2

JEE Main Chemistry Preparation 2025

Candidates can check the Chemistry preparation tips below to maximize their score in JEE Main Chemistry section.
  • Atomic Structure : Understand the basic model of the atom, including protons, neutrons, electrons, and quantum numbers. Familiarize yourself with the Bohr model and electron configuration.
  • Periodic Table Trends : Learn about trends such as atomic size, ionization energy, electron affinity, and electronegativity. Know how these properties change across periods and down groups.
  • Chemical Bonding : Master different types of bonds (ionic, covalent, metallic) and hybridization. Study VSEPR theory to predict molecular shapes.
  • Stoichiometry : Practice mole calculations, balancing equations, and using the concept of limiting reagents in reactions. Be comfortable with conversions between grams, moles, and molecules.
  • Thermochemistry : Focus on concepts like exothermic and endothermic reactions, Hess’s law, and calorimetry. Understand how to calculate enthalpy changes.
  • Chemical Equilibrium : Study the principles of dynamic equilibrium, the equilibrium constant (K), and how to shift equilibrium with changes in concentration, pressure, and temperature.
  • Redox Reactions : Learn to identify oxidation and reduction, assign oxidation states, and balance redox reactions using the half-reaction method.
  • Acids and Bases : Understand the Arrhenius, Brønsted-Lowry, and Lewis definitions. Study pH calculations, buffer solutions, and titration curves.
  • Kinetics : Familiarize yourself with rate laws, factors affecting reaction rates, and the concept of activation energy. Understand the Arrhenius equation.
  • Organic Chemistry Fundamentals : Focus on key functional groups, reaction mechanisms (like nucleophilic substitution and elimination), and basic synthesis routes. Know how to recognize and draw structures.

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Difference between Valency and Oxidation FAQs

Q1. What is the oxidation number of an element?

Ans. The oxidation number of an element may be fractional or whole. “Oxidation number denotes the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that electron pair in a covalent bond belongs entirely to a more electronegative element."

Q2. What does valency mean in chemistry?

Ans. The combining power or capacity of an element is known as its valency. However, valency is always a whole number.

Q3. Does oxygen have an oxidation number of 2?

Ans. The oxidation state of oxygen has 2, 2 and also 2, 2.

Q4. What is the major difference between valency and oxidation number?

Ans: Valency is the number of electrons present in the outermost shell of an atom. However, the oxidation number is the degree of oxidation gained, lost or shared of an element.
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