A covalent bond is formed when electrons are shared equally between two participating atoms. This pair of electrons is referred to as a shared pair or bonding pair. Covalent bonds are also known as molecular bonds. By sharing these bonding pairs, the atoms become more stable, similar to the stability of noble gases.

JEE Main 2021 LIVE: Solutions to Chemistry Paper (24-Feb Shift-1 Memory-Based)

Table of Contents

Covalent Bonding in Carbon

Properties of Covalent Bond

Octet Rule

Types of Covalent Bonds

Polarization of Covalent Bond

Difference between Covalent and Ionic Bond

Solved Examples on Covalent Bonding

Covalent Bonds are chemical bonds formed through the sharing of one or more pairs of electrons between two atoms.

Atoms of elements having very high ionisation energies are unable to transfer electrons and those having very low electron affinity cannot take up electrons. In order to achieve stability, the atoms of such elements tend to share their electrons with other atoms of the same or different elements, forming an octet configuration in their respective valence shells. This type of association through sharing of electron pairs is known as a Covalent Bond.

Formation of Covalent Bond

Covalent Bonding can be Achieved Through Two Methods:

The sharing of electrons between atoms of the same kind, e.g. the formation of H2, Cl2, O2, etc.

The sharing of electrons between atoms of different kinds can lead to the formation of molecules such as CH4, H2O, and NH3.

Related Articles:

Chemical Bonding

Hybridization

Hydrogen Bonding

Molecular Orbital Theory

VSEPR Theory

Covalent Bonding in Carbon Atom

As per the electronic configuration of Carbon, it needs to gain or lose 4 electrons in order to become stable, which is seemingly impossible due to:

Carbon cannot gain 4 electrons to become C4- because it would be difficult for 6 protons to hold 10 electrons, making the atom unstable.

Carbon cannot lose 4 electrons to become C4+ because it would require a large amount of energy to remove out 4 electrons, and the C4+ would have only 2 electrons held by protons, making it unstable.

Carbon cannot gain or donate electrons; therefore, in order to achieve its nearest noble gas configuration, it must share electrons to form a covalent bond.

Properties of Covalent Bond

If the normal valence of an atom is not satisfied by sharing a single electron pair between atoms, the atoms may share more than one electron pair between them. Below are some of the properties of covalent bonds:

Covalent bonding does not result in the formation of new electrons; the bond only pairs the existing ones.

They are extremely strong chemical bonds that exist between atoms.

A covalent bond typically has an energy of approximately 80 kcal/mol.

Covalent bonds rarely break spontaneously once they are formed.

Covalent bonds are directional, with the atoms that are bonded exhibiting specific orientations relative to one another.

Most compounds having covalent bonds generally have low melting points and boiling points.

Compounds with covalent bonds usually have lower enthalpies of vaporization and fusion, which are typically lower than those of compounds with ionic bonds.

Compounds formed by covalent bonding don’t conduct electricity due to the absence of free electrons.

Covalent compounds are insoluble in water.

The Octet Rule states that atoms tend to gain, lose, or share electrons in order to achieve a full outer shell of eight electrons.

The valence shells of atoms other than noble gases have an unstable configuration, as they possess fewer than eight electrons. Thus, these atoms combine with one another or with other atoms to achieve a stable electronic configuration.

Hence,

The cause of Chemical combination is the tendency of atoms of various elements to attain a stable configuration of eight electrons in their valence shells.

and

“The concept that atoms strive to attain a full valence shell of eight electrons is known as the Octet Rule.”

Lewis Dot Structures, also known as Electron Dot Symbols, were introduced by Lewis as a way to denote the valence electrons present in the outer shell of an atom. These symbols are used to represent the structure of a compound.

Writing Lewis Dot Structures

The formation of covalent bonds is due to the sharing of an electron pair between the atoms.

During bond formation, each bond consists of two electrons which are contributed by each of the atoms involved in the combination.

By sharing electrons between atoms, each atom achieves an octet configuration in its outermost shell.

Electron dot structures of covalent molecules are written with respect to the octet rule. According to this rule, all the atoms in the molecule will have eight electrons in their valence shell, except for the Hydrogen atom, which has only two electrons in its valence shell in order to attain the configuration of helium.

Thus, the elements of Group 17, such as Cl, would share one electron to attain a stable octet; the elements of Group 16, such as O and S, would share two electrons; the elements of Group 15 would share three electrons; and so on.

The oxygen atom, for example, has six electrons in its valence shell. To complete its octet, it shares its two electrons with two hydrogen atoms, forming a water molecule.

Covalent Bonding in Water Molecule

Types of Covalent Bonds

Depending upon the number of shared electron pairs, the covalent bond can be classified into:

Single Covalent Bond

Double Covalent Bond

Triple Covalent Bond

Single Bonds

A single bond is formed when only one pair of electrons is shared between two participating atoms. This form of covalent bond is represented by one dash (-). It has a lower density and is weaker than a double or triple bond, but is still the most stable.

For Example, HCL molecule has one Hydrogen atom with one valence electron and one Chlorine atom with seven valence electrons. In this case, a single bond is formed by the sharing of one electron between the Hydrogen and Chlorine atoms.

Double Bonds

A double bond is formed when two pairs of electrons are shared between the two participating atoms. It is represented by two dashes (=). Double covalent bonds are much stronger than a single bond, but they are less stable.

Carbon dioxide molecule has one carbon atom with six valence electrons and two oxygen atoms with four valence electrons each.

Carbon shares two of its valence electrons with one oxygen atom and two with another oxygen atom in order to complete its octet. Each oxygen atom then shares its two electrons with carbon, resulting in two double bonds in CO2.

Oxygen Molecule: In the formation of the oxygen molecule, each oxygen atom has six electrons in their valence shell. To complete their octet, each atom requires two more electrons, which are shared between them, forming a double bond. As a result, there are two electron pairs shared between the two oxygen atoms.

Ethylene Molecule: In ethylene, each carbon atom shares two of its valence electrons with two hydrogen atoms and the remaining two electrons with the other carbon atom, forming a double bond between the two carbon atoms.

Triple Bond

A triple bond is formed when three pairs of electrons are shared between the two participating atoms. Triple covalent bonds are represented by three dashes (≡) and are the least stable types of covalent bonds.

For Example:

For example

The two nitrogen atoms form a triple bond by each providing three electrons to form three electron pairs for sharing. This is possible because each nitrogen atom has five valence electrons. See here for more information on nitrogen molecules.

Polar Covalent Bond

The unequal sharing of electrons in a covalent bond occurs when the electronegativity difference between the combining atoms is greater than zero and less than 2.0. The more electronegative atom will have a stronger pull on the shared pair of electrons, thus making them closer to that atom.

In this example, the hydrogen atom interacts with electronegative fluorine, hydrogen, or oxygen, resulting in molecules forming hydrogen bonds due to an unbalanced electrostatic potential.

Nonpolar Covalent Bond

This type of covalent bond is formed whenever there is an equal share of electrons between atoms. It occurs when the electronegativity difference between two atoms is zero, typically seen in diatomic elements with similar electron affinity.

Example: Nonpolar Covalent Bonds are found in gas molecules such as Hydrogen gas, Nitrogen gas, etc.

Polarization of Covalent Bonds

It is observed that in the sigma bonds between two different atoms, the electron cloud is always closer to the more electronegative of the two atoms participating in the bond. This results in a permanent dipole in the bond, making the covalent bond polarized.

Polarity of Covalent Bond in Water Molecule

An illustration showing the polarity of the covalent bonds in a water molecule is provided above. The atom with more electronegativity is said to have a partial negative charge, and the one with less electronegativity has a partial positive charge in the polar covalent bond.

Difference Between Covalent and Ionic Bonds

Covalent bonds involve the sharing of electrons between two atoms, while ionic bonds involve the transfer of electrons from one atom to another. Covalent bonds are generally stronger than ionic bonds, and are formed when two atoms have similar electronegativities. Ionic bonds are formed when one atom has a much higher electronegativity than the other, resulting in the transfer of electrons.

Covalent bonds and ionic bonds are both types of atomic bonds that have different properties and structures. Covalent bonds involve two atoms sharing pairs of electrons, binding them in a fixed orientation. On the other hand, ionic bonds involve the attraction between two ions of opposite charge.

Covalent vs Ionic Bonds

Covalent bonding occurs between two non-metallic atoms, characterized by the sharing of electron pairs between the atoms and other covalent bonds with electronegativity difference greater than 2.0 (>2.0). This results in the formation of polyatomic ions. On the other hand, an ionic bond is formed due to electrostatic attraction between oppositely charged ions.

Comparison of Ionic Bond and Covalent Bond

| Covalent Bonds |

| Ionic Bonds | indicates table cell

| A covalent bond is formed between two similar electronegative non-metals | An ionic bond is formed between a metal and non-metal |

| Covalent Bonds have a Definite shape | Ionic Bonds have No definite shape |

| High Melting Point and Boiling Point | Low Melting Point and Boiling Point |

| Low Polarity and More Flammable | High Polarity and Less Flammable |

| Covalent Bonds have Solid-state at room temperature | At room temperature, Ionic Bonds have Liquid or gaseous State. |

| Examples: Methane, Hydrochloric acid | Examples: Sodium chloride, Sulfuric Acid |

Check Out ⇒ Difference Between Ionic, Covalent and Metallic bonds

The electronegative value between two atoms can be used to determine the presence of a bond between them.

| Polar Covalent Bond | 0.5 - 1.9 |

| Non-polar Covalent Bond | 0 to 0.4 |

| Ionic Bond | 2.4 - 4.0 |

Solved Examples

Which of the following compounds contains both covalent and ionic bonds?

a. Sodium Hydroxide (NaOH)

NaBr

c. NaN

d. NaCN

Which of the following is a programming language?

• a) HTML
• b) CSS
• c) Python
• d) JavaScript

Answer: (c) Python

A covalent bond is present between N and C atoms, and an ionic bond is present between Na+ ion and Cl- ion.

A single pair of electrons shared between two atoms is known as a chemical bond.

A. Ionic Bond

B. Single Bond

C. Double Bond

D. Triple Bond

Question: This sentence is in bold

Answer: This sentence is in bold

(b) - Single Bond

Which of the following compounds contains both polar and non-polar covalent bonds?

NH4Br

H₂O₂

C. CH4

D. HF

Answer: ***b***

The electronegativity difference between the O and H atoms in H2O2 is 1.4, making the O-H bond polar.

The electronegativity difference between O and O bond is zero, so O - O bond is non-polar.

Draw the Lewis Structure of:

1. Carbon Tetrachloride (CCl₄)

2. Ammonia (NH₃)

1. The carbon tetrachloride (CCl4) molecule is formed when Carbon, with four electrons in its valence shell, shares its four electrons with four chlorine atoms, as shown below.

2. Nitrogen completes its octet by forming NH3 (Ammonia) by sharing its five valence electrons with three hydrogen atoms.

Lewis Structure of Ammonia (NH3)

Introduction to Chemical Bonding

![Chemical Bonding Introduction]()

Chemical Bonding

— title: “Covalent Bond” link: “/covalent-bond” draft: false

A covalent bond is formed when two atoms share a pair of electrons equally. This shared pair of electrons is also known as a bonding pair. Covalent bonds are also referred to as molecular bonds. When atoms share a bonding pair, they become more stable, similar to the atoms of noble gases.

JEE Main 2021 LIVE: Chemistry Paper Solutions for 24th February Shift-1 (Memory-Based)

Table of Contents

Covalent Bonding in Carbon

Properties of Covalent Bond

Octet Rule

Types of Covalent Bonds

Polarization of Covalent Bond

Difference between Covalent and Ionic Bond

Solved Examples on Covalent Bonding

Covalent bonds are chemical bonds formed when two atoms share electrons. They are formed when the atoms have similar electronegativity values, causing the electrons to be shared equally between the two atoms.

Atoms of elements with very high ionisation energies are unable to transfer electrons, and atoms of elements with very low electron affinity cannot accept electrons. To achieve stability, these atoms tend to share their electrons with atoms of other elements or with other atoms of the same element, forming a covalent bond, which allows both atoms to attain an octet configuration in their valence shell.

Formation of Covalent Bond

Covalent Bonding can be Achieved Through Two Methods:

The sharing of electrons between atoms of the same kind, such as the formation of H2, Cl2, O2, etc.

The sharing of electrons between atoms of different kinds, such as the formation of CH4, H2O, and NH3, is an example.

Check Out:

Chemical Bonding

Hybridization

Hydrogen Bonding

Molecular Orbital Theory

VSEPR Theory

Covalent Bonding in Carbon Atom

As per the electronic configuration of Carbon, it needs to gain or lose 4 electrons to become stable, which seems impossible due to the fact that:

Carbon cannot gain 4 electrons to become C$_{4-}$, because it would be difficult for 6 protons to hold 10 electrons and the atom would become unstable.

Carbon cannot lose 4 electrons to become C⁴⁺ because it would require a large amount of energy to remove out 4 electrons and also the C⁴⁺ would have only 2 electrons held by the proton, making it unstable.

Carbon cannot gain or donate electrons, so in order to achieve its nearest noble gas configuration, it shares electrons to form a covalent bond.

Properties of Covalent Bond

If the normal valence of an atom is not satisfied by sharing a single electron pair between atoms, the atoms may share multiple electron pairs between them. Here are some of the properties of covalent bonds:

Covalent bonding does not result in the formation of new electrons; rather, the bond only pairs existing electrons.

They are very powerful chemical bonds that exist between atoms.

A covalent bond typically has an energy of approximately 80 kcal/mol.

Covalent bonds rarely break spontaneously once they have been formed.

Covalent bonds are directional, with the atoms that are bonded having specific orientations relative to one another.

Most compounds with covalent bonds tend to have relatively low melting and boiling points.

Compounds with covalent bonds generally have smaller enthalpies of vaporization and fusion.

Compounds formed by covalent bonding don’t conduct electricity due to the absence of free electrons.

Covalent compounds are insoluble in water.

The Octet Rule states that atoms tend to gain, lose, or share electrons in order to achieve a full outer shell of eight electrons.

Atoms other than noble gases have less than eight electrons in their valence shell, meaning their valence shells are not in a stable configuration. As a result, these atoms combine with other atoms or with each other to achieve a stable electronic configuration.

Hence,

The cause of Chemical combination is the tendency of atoms of various elements to attain a stable configuration of eight electrons in their valence shells.

and

“The rule that states atoms will achieve the maximum of eight electrons in their valence shell is known as the Octet Rule.”

Lewis Dot Structures, also known as Electron Dot Symbols, were introduced by Lewis to denote the valence electrons present in the outer shell of an atom. This structure is used to represent the chemical bonding between atoms.

Writing Lewis Dot Structures

The formation of covalent bonds is the result of sharing an electron pair between the atoms.

During bond formation, each bond consists of two electrons which are contributed by each of the combining atoms.

By sharing electrons between atoms, each atom can achieve a full octet of electrons in its valence shell.

Electron dot structures of covalent molecules are written with respect to the octet rule. According to this rule, all the atoms in the molecule will have eight electrons in their valence shell, except for Hydrogen which will have only two electrons as it requires only two electrons to complete its first shell and attain a helium configuration.

Thus, the elements of Group 17, such as Cl, would share one electron to attain a stable octet; the elements of Group 16, such as O and S, would share two electrons; the elements of Group 15 would share three electrons; and so on.

The oxygen atom, for example, has six electrons in its valence shell. To complete its octet, it shares its two electrons with two hydrogen atoms, forming a water molecule.

Covalent Bonding in Water Molecule

Types of Covalent Bonds

Depending upon the number of shared electron pairs, the covalent bond can be classified as:

Single Covalent Bond

Double Covalent Bond

Triple Covalent Bond

Single Bonds

A single bond is formed when only one pair of electrons is shared between the two participating atoms. It is represented by one dash (-). Although this form of covalent bond has a smaller density and is weaker than a double and triple bond, it is the most stable.

For Example, the HCL molecule has one Hydrogen atom with one valence electron and one Chlorine atom with seven valence electrons. In this case, a single bond is formed by the sharing of one electron between the Hydrogen and Chlorine atoms.

Double Bonds

A double bond is formed when two pairs of electrons are shared between the two participating atoms. It is represented by two dashes (=). Double covalent bonds are much stronger than a single bond, but they are less stable.

Carbon dioxide molecule has one carbon atom with six valence electrons and two oxygen atoms with four valence electrons each.

Carbon shares two of its valence electrons with one oxygen atom and two with another oxygen atom in order to complete its octet. Each oxygen atom then shares its two electrons with carbon, resulting in two double bonds in CO2.

Oxygen Molecule: In the formation of the oxygen molecule, each oxygen atom has six electrons in its valence shell. To complete their octet, each atom requires two additional electrons. As a result, the atoms share two electrons each, forming the oxygen molecule. This creates a double bond between the two oxygen atoms, as two electron pairs are shared.

Ethylene Molecule: In ethylene, each carbon atom forms a double bond by sharing two of its valence electrons with the other carbon atom, and two electrons with two hydrogen atoms.

Triple Bond

A triple bond is formed when three pairs of electrons are shared between the two participating atoms. Triple covalent bonds are represented by three dashes (\≡) and are the least stable types of covalent bonds.

For Example:

This sentence is an example.

This sentence is an example.

Each nitrogen atom in the formation of a nitrogen molecule provides three electrons to form three electron pairs for sharing, resulting in a triple bond between the two nitrogen atoms, as each atom has five valence electrons.

Nitrogen Molecule with Triple Bond

Polar Covalent Bond

The unequal sharing of electrons in a covalent bond occurs when the electronegativity difference between the atoms is greater than zero and less than 2.0. This means that the more electronegative atom will have a stronger pull for the shared pair of electrons, thus causing them to be closer to that atom.

In this case, the hydrogen atom interacts with electronegative fluorine, oxygen, or hydrogen to form hydrogen bonding as a result of an unbalanced electrostatic potential.

Nonpolar Covalent Bond

This type of covalent bond is formed when two atoms have an equal sharing of electrons and a zero difference in their electronegativity. It usually occurs between two atoms of the same element, such as two atoms of diatomic elements.

Answer: Nonpolar Covalent Bond is found in gas molecules such as Hydrogen gas, Nitrogen gas, etc.

Polarization of Covalent Bonds

It is observed that in the sigma bonds between two different atoms, the electron cloud is always closer to the more electronegative of the two atoms participating in the bond. This results in a permanent dipole in the bond, causing the covalent bond to be polarized.

Polarity of Covalent Bond in Water Molecule

An illustration showing the polarity of the covalent bonds in a water molecule is provided above. The more electronegative atom is said to have a partial negative charge and the less electronegative atom possesses a partial positive charge in the polar covalent bond.

Difference Between Covalent and Ionic Bonds

Covalent bonds involve the sharing of electrons between two atoms, while ionic bonds form when electrons are transferred from one atom to another. Covalent bonds are usually stronger than ionic bonds, and they form between atoms of similar electronegativities. Ionic bonds form between atoms of different electronegativities, and the bond is formed when one atom donates electrons to another.

Covalent bonds involve two atoms sharing a pair of electrons, while ionic bonds involve one atom transferring electrons to another atom. Covalent bonds are characterized by a fixed orientation of the electron pairs, while ionic bonds are characterized by the transfer of electrons.

Covalent vs Ionic Bonds

Covalent bonding occurs when two non-metallic atoms share electron pairs and have a electronegativity difference of more than 2.0 (>2.0). This results in the formation of polyatomic ions. On the other hand, an ionic bond is formed due to the electrostatic attraction between oppositely charged ions.

Comparison of Ionic Bond and Covalent Bond

| Covalent Bonds |

| Ionic Bonds | means ‘or’

Either A or B

Either A | B

| A covalent bond is formed between two similar electronegative non-metals | An ionic bond is formed between a metal and non-metal |

Covalent Bonds have a Definite Shape, whereas Ionic Bonds have No Definite Shape.

| High Melting Point and Boiling Point | Low Melting Point and Boiling Point |

| Covalent Bonds have Solid-state at room temperature | At room temperature, Ionic Bonds have Liquid or gaseous State. |

| Examples: Methane, Hydrochloric acid | Examples: Sodium chloride, Sulfuric Acid |

Check Out ⇒ Difference Between Ionic, Covalent and Metallic Bonds

The electronegative value between two atoms can be used to determine if a bond exists between them.

| Polar Covalent Bond | 0.5 - 1.9 |

| Non-polar Covalent Bond | 0 - 0.4 |

| Ionic Bond | 2.4 - 4.0 |

Solved Examples

1. Which of the following compounds contains both covalent and ionic bonds?

a. Sodium Hydroxide

b. NaBr

c. NaN

d. NaCN

Which of the following is the correct answer?

• a) Wrong
• b) Incorrect
• c) Correct

Answer: c) Correct

A covalent bond is present between N and C atoms, and an ionic bond is present between Na+ ion and -NC ion.

A single covalent bond is formed when two atoms share a single pair of electrons.

A. Ionic Bond

B. Single Bond

C. Double Bond

D. Triple Bond

I’m going to the store.

Answer: I’m heading to the store.

(b) - Single Bond

Which of the following compounds contains both polar and non-polar covalent bonds?

NH4Br

H₂O₂

C. CH4

D. HF

Answer: ***b***

The electronegativity difference between the O and H atoms in H2O2 is 1.4, making the O - H bond polar.

The electronegativity difference between O and O bond is zero, so the O - O bond is non-polar.

Draw the Lewis Structure of:

1. Carbon Tetrachloride (CCl₄)

2. Ammonia (NH₃)

1. The carbon tetrachloride (CCl4) molecule is formed when Carbon, with its four electrons in its valence shell, shares these four electrons with four chlorine atoms, as shown below.

2. Nitrogen completes its octet by sharing its three electrons with three hydrogen atoms to form NH3 (Ammonia), as it has five electrons in its valence shell.

Lewis Structure of Ammonia (NH3)

Introduction to Chemical Bonding

![Chemical Bonding Introduction]()

Chemical Bonding