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Difference Between Molecule and Compound

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Last updated date: 17th Apr 2024
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What is Molecule and Compound: Introduction

In the world of chemistry, molecules and compounds are two essential concepts that form the building blocks of matter. Understanding the difference between molecule and compound is crucial for grasping the fundamental principles of chemistry and how substances interact with one another. In this introduction, we will explore the definitions and introductory concepts of molecules and compounds, setting the stage for a deeper exploration of their characteristics and distinctions.


Defining Molecule

A molecule can be thought of as the smallest unit of a substance that retains its chemical properties. It is made up of atoms that have been chemically bonded by two or more. Atoms from the same element or from other elements can combine to form molecules.

For example, oxygen gas (O2) is a molecule made up of two oxygen atoms bonded together, while water (H2O) is a molecule consisting of two hydrogen atoms and one oxygen atom bonded together. Molecules can exist independently and have specific physical and chemical properties.


Defining Compound

A compound is a molecule, made up of two or more different components that have been chemically bonded together in a certain order. Compounds are formed through chemical reactions, where atoms of different elements come together and bond to create a new substance. Each compound has a unique chemical formula that represents the ratio of elements present.


For instance, sodium chloride (NaCl) is a compound composed of one sodium atom bonded to one chlorine atom. Compounds have distinct properties that differ from the elements they are composed of.

Characteristics of Molecule and Compound

Let’s learn more about the characteristics of molecule and compounds to understand about their differences.


Characteristics of Molecules

Composition: Molecules are composed of two or more atoms chemically bonded together. The atoms may be of the same element or may be of different elements.


Size: Molecules can vary in size, ranging from small molecules with just a few atoms to large complex molecules containing hundreds or even thousands of atoms.


Stability: Molecules are generally stable entities and can exist independently. They have specific chemical properties and can undergo chemical reactions to form new molecules.


Physical Properties: Molecules have unique physical properties such as melting point, boiling point, density, and solubility, which are determined by the types and arrangement of atoms within the molecule.


Molecular Formula: Each molecule has a molecular formula that represents the types and number of atoms present in the molecule. For instance, the molecular formula of water is H2O, which denotes the presence of two hydrogen atoms and one oxygen atom.


Characteristics of Compounds

Composition: Compounds are composed of two or more different elements chemically bonded together. They have a fixed ratio of elements in their chemical formula.


Formation: Compounds are formed through chemical reactions where atoms of different elements combine to create a new substance with unique properties.


Chemical Properties: Compounds have distinct chemical properties that differ from the elements they are composed of. They can react with other substances in characteristic ways, undergoing chemical changes.


Physical Properties: Compounds have specific physical properties such as color, odor, taste, and texture that are different from the elements they are made of.


Chemical Formula: Each compound has a chemical formula that represents the elements present and their ratio. The chemical formula of sodium chloride is NaCl, indicating one sodium atom and one chlorine atom.


Stability: Compounds are generally stable and can exist as discrete entities. They have specific chemical properties that are different from their constituent elements.


Energy Changes: Chemical reactions involving compounds often involve energy changes, such as the release or absorption of heat or light.


Difference Between Molecule and Compound

Sr. No.

Category

Molecule

Compound

1

Definition

A group of two or more atoms bonded together, either of the same element or different elements.

A specific type of molecule that consists of different elements chemically bonded together.

2

Composition


Can be composed of the same or different elements.

Always composed of different elements.

3

Bonding

Atoms are held together by covalent bonds.

Atoms are held together by chemical bonds (ionic or covalent). 

4

Representation

Represented by a molecular formula or structural formula.

Represented by a chemical formula indicating the types and ratios of atoms present.


5

Examples

O2 (oxygen gas), N2 (nitrogen gas), H2O (water)

H2O (water), CO2 (carbon dioxide), NaCl (sodium chloride) 

6

Properties

Retains the properties of the individual atoms or elements.

Exhibits unique properties different from the constituent elements.


Summary

Molecules and compounds are fundamental concepts in chemistry. A molecule is made up of two or more atoms that are joined by chemical bonds. It represents the smallest unit of a chemical substance that retains its chemical properties. Compounds, on the other hand, are molecules that consist of atoms from different elements. They are formed when atoms of different elements chemically combine in fixed ratios. The key difference between molecules and compounds lies in their composition. Molecules can be made up of atoms of the same element (e.g., O2, N2) or different elements (e.g., H2O, CO2), while compounds are always composed of different elements (e.g., H2O, CO2). Compounds have specific chemical formulas and distinct properties, whereas molecules can be individual elements or combinations of elements.

FAQs on Difference Between Molecule and Compound

1. What distinguishes a compound from a molecule?

A molecule is a group of two or more atoms bonded together, regardless of the elements involved. It can be a single element (e.g., O2) or a combination of different elements (e.g., H2O). A compound, on the other hand, is a specific type of molecule that consists of different elements chemically bonded together, forming a distinct substance with its own unique properties.

2. Can a molecule be a compound?

Yes, a molecule can be a compound if it is composed of different elements. Compounds are a subset of molecules that have specific chemical formulas and consist of different types of atoms bonded together.

3. Are all compounds molecules?

Yes, all compounds are molecules because they are formed by the bonding of atoms. However, not all molecules are compounds. Molecules that consist of a single element, such as O2 or N2, are not considered compounds because they are made up of the same type of atom. Compounds, on the other hand, are molecules that contain multiple elements bonded together.