Short Answer

A covalent compound is a substance formed when two or more nonmetal atoms share electrons to achieve stability. Instead of transferring electrons like in ionic compounds, the atoms in a covalent compound share electron pairs. This sharing creates a covalent bond that holds the atoms together. Examples include water (H₂O), carbon dioxide (CO₂), and methane (CH₄).

Covalent compounds usually have low melting and boiling points, and many of them exist as gases or liquids at room temperature. They do not conduct electricity because they do not form ions. These compounds are found widely in living organisms and everyday materials.

Detailed Explanation

Covalent compound

A covalent compound is formed when atoms, usually nonmetals, share electrons with each other in order to achieve a stable electron configuration. This shared pair of electrons creates a covalent bond. Unlike ionic compounds, where electrons are transferred from one atom to another, covalent bonding involves mutual sharing. This type of bonding is essential for forming molecules that play major roles in chemistry, biology, and daily life.

Atoms form covalent compounds to complete their valence shells. Most atoms aim to follow the octet rule, which states that atoms become stable when they have eight electrons in their outermost shell. Hydrogen is an exception because it needs only two electrons to become stable. By sharing electrons, atoms help each other achieve this stable configuration.

Covalent compounds can consist of just two atoms, like hydrogen gas (H₂), or can form very large and complex molecules, such as proteins, DNA, and plastics. The variety and flexibility of covalent bonding make it the foundation of organic chemistry and the basis of life on Earth.

Formation of covalent compounds

Covalent compounds form through the sharing of electrons between atoms:

1. Two nonmetal atoms come close together.
2. Their valence electrons interact.
3. The atoms share one or more pairs of electrons.
4. A covalent bond is formed.

Depending on how many electron pairs are shared, covalent bonds may be:

• Single bond: Sharing one pair of electrons (e.g., H–H in hydrogen gas).
• Double bond: Sharing two pairs of electrons (e.g., O=O in oxygen gas).
• Triple bond: Sharing three pairs of electrons (e.g., N≡N in nitrogen gas).

These shared electrons hold the atoms together in a molecule.

Properties of covalent compounds

Covalent compounds show several important physical and chemical properties:

1. Low melting and boiling points

The forces between molecules in covalent compounds are often weak. As a result, covalent compounds melt and boil at lower temperatures compared to ionic compounds. Many exist as gases or liquids at room temperature.

Examples:

• Oxygen (O₂) – gas
• Water (H₂O) – liquid
• Carbon dioxide (CO₂) – gas

2. Do not conduct electricity

Covalent compounds do not form ions. Since electricity requires charged particles to move, these compounds cannot conduct electricity in solid, liquid, or dissolved form (except a few cases like acids when ionized in water).

3. Usually soluble in organic solvents

Covalent compounds dissolve easily in solvents like alcohol, benzene, and ether but not in water.

4. Can form soft solids

Some covalent compounds form soft solids like wax, sugar, and plastic. These solids do not have strong forces like ionic crystals.

5. Variable reactivity

Some covalent compounds like methane burn easily, while others like nitrogen gas are very unreactive because of strong triple bonds.

Examples of covalent compounds

Common covalent compounds include:

• Water (H₂O)
• Carbon dioxide (CO₂)
• Methane (CH₄)
• Ammonia (NH₃)
• Hydrogen gas (H₂)
• Nitrogen gas (N₂)

More complex examples include:

• Glucose (C₆H₁₂O₆)
• DNA molecules
• Plastics and polymers

These compounds form the basis of life, food, and many everyday materials.

Importance of covalent compounds

Covalent compounds are essential in many areas:

1. Living organisms

All biological molecules—proteins, carbohydrates, fats, vitamins—are covalent compounds.

2. Environment

Major atmospheric gases like oxygen, nitrogen, and carbon dioxide are covalent molecules.

3. Industry

Plastics, rubber, fuels, detergents, and dyes are covalent compounds.

4. Household use

Soap, sugar, oils, and many cleaning products are made of covalent substances.

Difference from ionic compounds (brief clarity)

• Covalent compounds share electrons between nonmetals.
• Ionic compounds involve electron transfer between metals and nonmetals.

This difference explains why covalent compounds tend to be softer, have lower melting points, and do not conduct electricity.

Conclusion

A covalent compound is formed when atoms share electrons to create stable molecules. These compounds usually involve nonmetal atoms and can be simple or extremely complex. Covalent compounds have unique properties such as low melting points, poor electrical conductivity, and wide presence in living organisms. Covalent bonding is essential for forming the molecules that make up life, materials, and the environment around us.