Covalent Bonding: Understand Its Definition, Types, Properties, and Examples with Diagrams

Introduction to Covalent Bonding

We know that atoms join together to form molecules or compounds to gain stability. One important way is by sharing their electrons in the outermost shell between non-metal atoms. 

Understanding the covalent bond is important to learn how atoms share electrons to form molecules. This blog will explore the basics of covalent bonds, their types, and properties, providing clear explanations and examples.

What is a Covalent Bond?

When two nonmetal atoms share one or more electron pairs, a strong bond is formed that holds the atoms together in a molecule. This bond is called a covalent bond. In this way, atoms attain the electronic configuration of noble gases.

Types of Covalent Bond Explained with Examples

The covalent bond is classified based on how many pairs of electrons are shared.

Single Covalent Bond

It is the type of covalent bond in which only one pair of electrons between two atoms is shared.

Example

Hydrogen gas (H2)

The hydrogen atom has only one electron in its outermost shell. A hydrogen atom must have two electrons to gain stability and attain the electronic configuration of a noble gas, Helium. To do this, two hydrogen atoms overlap and share one electron pair, forming a hydrogen molecule (H-H).

It is represented by a single straight line (-)

Double covalent bond

It involves the sharing of two electron pairs between two atoms.

Example

Carbon dioxide (CO2)

Carbon belongs to Group IV and has four electrons in its outer shell. It requires four more electrons to become stable and achieve the electronic configuration of a noble gas, Neon.

Oxygen belongs to Group VI and has six electrons in its outer shell. It requires two electrons to complete its octet and achieve the electronic configuration of Neon.

Carbon forms two double covalent bonds with oxygen by sharing two electron pairs (O=C=O)

The double covalent bond is represented by two straight lines (=)

Triple Covalent Bond

It involves the sharing of three electron pairs between two atoms.

Example

Nitrogen gas (N2)

Each nitrogen atom has five electrons in its outer shell. It requires three more electrons to attain the electronic configuration of the noble gas Neon. Both nitrogen atoms overlap and share three electron pairs and form a stable molecule, i.e, Nitrogen gas (N≡N)

The triple bond is represented by three straight lines (≡)

Polar and Nonpolar Covalent Bonds

In a Polar Covalent Bond, electrons are not shared equally due to the significant difference in electronegativity between the atoms. The electrons are not evenly distributed, leading to partial charges on atoms, causing a dipole moment.

The bond between hydrogen and oxygen in water is the classic example of a polar covalent bond.

In a nonpolar covalent bond, electrons are equally shared between the atoms. It mostly occurs between atoms with similar electronegativity.

If the covalent bond is symmetrical, the charges are evenly spread across the molecule. As a result, dipole charges cancel out each other, and the compound is considered nonpolar.

The example of a nonpolar covalent bond is the Chlorine molecule. 

Properties of Covalent Compounds

Melting and Boiling Points

Simple molecular covalent compounds are usually gases or liquids with low melting and boiling points. This is due to the presence of weak intermolecular forces between molecules. It is important to note that ionic compounds have higher melting and boiling points than covalent molecules due to the strong electrostatic force of attraction between oppositely charged ions.

Electrical Conductivity

Usually, covalent compounds do not conduct electricity in any state, but some covalent molecules react with water and form ions. The presence of ions allows them to conduct electricity.

Solubility

Polar covalent compounds may dissolve in water, however, nonpolar compounds do not. Generally, covalent compounds dissolve in organic solvents.

Covalent Bonding Question & Answers for Students

Why is methane (CH₃) considered a nonpolar molecule?

The structure of methane is symmetrical and tetrahedral, and the electronegativity difference between carbon and hydrogen is minimal. Because of equal sharing of electrons and its symmetrical structure, methane is a nonpolar molecule.

Why is hydrogen (H₂) a gas while water is a liquid? OR Why are larger molecules liquid?

As the size of the molecule increases, the intermolecular forces between molecules also become stronger. This increased force of attraction pulls molecules close together. Since hydrogen is a very small molecule, the intermolecular forces are weak in hydrogen as compared to water. 

Conclusion

Covalent bonding is a fundamental concept that explains how atoms share electrons and form stable molecules. Understanding the different types of covalent bonds and their properties is important for analyzing the structure and behaviour of various compounds.

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