What are Compounds?


It is a substance which is made up of 2 or more elements

They are chemically combined together in a fixed proportion. 



Carbon Dioxide (CO 2 )

One compound of CO 2 is made up of 1 Atom of Carbon and 2 atoms of Oxygen

Water (H 2 O)

One atom of H 2 O is made up of 2 Atoms of Hydrogen and 1 atom of Oxygen


A compound contains at least 2 type of Elements


Oxygen (O 2 ) is not a compound   

as it contains only one type of element (O)

Water (H 2 O) is a compound  

as it contains 2 elements of Hydrogen and 1 of Oxygen

Sulphuric Acid (H 2 SO 4 ) is a compound  

as it contains 3 type of element Hydrogen (H),Sulphur (S) and Oxygen (O)

Properties of Compound are Different from its Elements



Property of Water (H 2 O) is different from the properties of Hydrogen and Oxygen.


Different Elements of a compound cannot be Separated by Physical Methods

We cannot use physical methods like filtration, evaporation, sublimation etc. to separate  Hydrogen and Oxygen from Water.

We have to use chemical or electrochemical reactions to do the same


Elements React to Form compounds

There is a reaction between 2 or more elements to form a compound

Just mixing of 2 or more elements do not create compound

Example - Water is not just created by mixing Hydrogen and Water

A proper reaction  needs to take place between 2 atoms of Hydrogen and 1 Atom of Oxygen to create water


  1. Class 9
  2. Chapter 2 Class 9 - Is Matter Around Us Pure

About the Author

Davneet Singh's photo - Teacher, Computer Engineer, Marketer
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.