What is Molecule | Types of Molecules, Example

Molecules are essential building blocks of everything around us. They are tiny particles that comprise atoms bonded together in a specific way.

Molecules are the foundation of all living things and non-living things. Understanding what a molecule is and how it works is fundamental to many fields of study, including chemistry, physics, and biology.

In this tutorial, we will understand what a molecule is, types of molecules, and the role it plays in our daily lives.

What is a Molecule?

In general, a molecule is a group of two or more atoms that are chemically bonded together. It is formed when two or more atoms of the same elements or of different elements combine together by chemical combination.

For example, O2 consists of atoms of the same element, while water (H2O) consists of atoms of different elements. A force of attraction known as chemical bond combine and hold atoms in a molecule together.

The chemical bond that binds atoms in molecules together is formed when two atoms share one or more electrons, and achieve a more stable configuration.

Molecules can come in different shapes and sizes, depending on the types and the number of atoms in the molecule. For example, a water molecule comprises two hydrogen atoms and one oxygen atom, and has a bent shape. On the other hand, a carbon dioxide molecule comprises one carbon atom and two oxygen atoms, and has a linear shape.

The properties of a molecule, such as its shape and size, determine its chemical and physical properties. For example, water molecules contain a strong force of attraction that helps in combining with each other. That’s why water molecules form droplets and have a high boiling point. Carbon dioxide, on the other hand, is a gas at room temperature and has a low boiling point.

Role of Molecules in Our Daily Lives

Molecules are present in everything around us, from the food we eat to the air we breathe. They play a significant role in many processes that occur in our bodies and in the natural world. One of the most important roles of molecules is in the chemical reactions that occur in our bodies. For example, when we eat food, molecules in the food are broken down into smaller molecules with the help of enzymes that our bodies consume for energy. This process is called digestion.

Molecules are also responsible for the smells and tastes that we experience in our daily lives. For example, the smell of a rose comes from the molecules that are released by the flower. The taste of food is also determined by the molecules that are present in the food.

Besides their role in the natural world, molecules are also used in many man-made products. For example, plastics are composed of long chains of molecules called polymers. These polymers have distinct properties, depending on their size and shape. They can be used for a wide range of applications.

Types of Molecules based on their Composition and Structure

We can classify molecules into different types based on their composition and structure. The most common classification is organic and inorganic molecules.

Organic molecules are those that contain carbon atoms and are mainly associated with living organisms. On the other hand, inorganic molecules do not contain carbon atoms and are often associated with non-living things.

Classification of Molecules based on Atomicity

In addition to organic and inorganic molecules, we can also classify molecules based on the atomicity. The number of atoms present in a molecule is known as atomicity.

  • Monoatomic
  • Diatomic
  • Triatomic
  • Tetra-atomic
  • Ployatomic

(1) Monoatomic molecules are those that composed of only one atom. The examples of monoatomic molecules are noble gases, such as helium, neon, krypton, and argon, which stay as single atoms and do not bond with other atoms. Monoatomic molecules are typically chemically inert, meaning they do not react with other elements.

(2) Diatomic molecules consist of two atoms of the same or different elements that are chemically bonded together. For example, oxygen is not stable in atomic form. It is stable in molecular form. A molecule of oxygen is diatomic in nature, meaning that its molecule consists of two oxygen atoms. Hydrogen (H2), nitrogen (N2), fluorine (F2), chlorine (Cl2), bromine (Br2), iodine (I2) are also diatomic, like oxygen. Diatomic molecules are held together by covalent bonds in which the atoms share electrons.

Diatomic molecules have crucial roles in many natural and industrial processes. For example, oxygen is essential for respiration in living organisms. Nitrogen is a key constituent of the atmosphere of the earth. Chlorine is used in water treatment to kill bacteria and other harmful organisms.

(3) Triatomic molecules consists of three atoms. Example of such molecules are O3, NO2, CO2, etc.

(4) Tetra-atomic molecules consist of four atoms. Example of such molecules are P4, H2O2, etc.

(5) Polyatomic molecules consist of more than four atoms. Example of such molecules are CH4, S8, etc.

Classification of Molecules based on Polarity

We can also classify molecules based on their polarity, which is determined by the distribution of electrons in the molecule.

Polar molecules contain an uneven distribution of electrons, which gives them a positive and negative end. For example, water is a polar molecule, that is why it has a powerful attraction to other polar molecules like itself.

On the other hand, nonpolar molecules contain an even distribution of electrons and do not have a positive or negative end.

Macromolecule is another type of molecule that is a large molecule composed of smaller units called monomers. Examples of macromolecules are carbohydrates, proteins, and nucleic acids.

Molecules of Compounds

Atoms of distinct elements combine together in definite proportions and form molecules of compounds. The names and formulae of some important common chemical compounds are as below in the table.

CompoundCombining ElementsRatio by Mass
1. Water (H2O)Hydrogen and Oxygen1 : 8
2. Ammonia (NH3)Nitrogen and Hydrogen14 : 3
3. Carbon dioxide (CO2)Carbon and Oxygen3 : 8
4. Hydrogen Sulphide (H2S)Hydrogen and Sulphur1 : 16
5. Sulphuric acid (H2SO4)Hydrogen, Sulphur, and Oxygen1 : 16 : 32
6. Glucose (C6H12O6)Carbon, Hydrogen, and Oxygen6 : 1 : 8
7. Baking powder (NaHCO3)Sodium, Hydrogen, Carbon, and Oxygen23 : 1 : 12 : 48
8. Common salt (NaCl)Sodium, and Chlorine23 : 35.5
9. Limestone (CaCO3)Calcium, Carbon, and Oxygen40 : 12 : 48
10. Calcium carbonate (CaCO3)Calcium, Carbon, and Oxygen10 : 3 : 12
11. Caustic soda (NaOH)Sodium, Hydrogen, and Oxygen23 : 16 : 1
12. Caustic potash (KOH)Potassium, Oxygen, and Hydrogen39 : 16 : 1
13. Ethanol (C2H5OH)Carbon, Hydrogen, and Oxygen12 : 3 : 8
14. Methanol (CH3OH)Carbon, Hydrogen, and Oxygen3 : 1 : 4
15. Ethyne (C2H2)Carbon, and Hydrogen12 : 1

Applications of Molecule Research

The study of molecules has many practical applications in various fields. For example, in the field of medicine, researchers study molecules that make up cells and tissues to better understand diseases and develop new treatments. In the field of materials science, researchers study the properties of molecules to develop new materials with specific properties.

In environmental science, molecules are studied to understand how pollutants and other chemicals impact the environment. By studying the behavior of molecules in the environment, researchers can develop strategies for reducing pollution and protecting natural resources.

Molecules are also being studied for their potential in new technologies. For example, researchers are exploring the use of molecules in nanotechnology, which involves creating tiny structures that can be used in electronics, medicine, and other fields.


In this tutorial, you have known about what is molecule, its role in our daily lives, types of molecules based on their composition and structure. Basically, molecules are essential building blocks of everything around us. They are responsible for the chemical and physical properties of substances.

They play a significant role in many processes that take place in our bodies as well as in the natural world. Hope that you will have understood all the basic points of molecules.
Thanks for reading!!!

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