Read and download the CBSE Class 9 Science Atoms and Molecules Exam Notes. Designed for 2026-27, this advanced study material provides Class 9 Science students with detailed revision notes, sure-shot questions, and detailed answers. Prepared by expert teachers and they follow the latest CBSE, NCERT, and KVS guidelines to ensure you get best scores.
Useful Resources: Class 9 Science Chapter 3 Atoms and Molecules
Want to score higher in Science? Going beyond regular textbooks is very helpful. This Class 9 Chapter 3 Atoms and Molecules study material brings you clear concept summaries and solved practice problems to build deeper understanding.
Class 9 Science Chapter 3 Atoms and Molecules Notes and Questions
CBSE Class 9 Science Atoms and Molecules Exam Notes. Please refer to the examination notes which you can use for preparing and revising for exams. These notes will help you to revise the concepts quickly and get good marks.
Introduction
Matter is called ‘padarth’ in Hindi. Kanad was one of the first persons to propose that matter (or padarth) is made
up of very small particles called ‘parmanu’. John Dalton called these particles by the name of atom. The word
‘atom’ means ‘indivisible’ something which cannot be divided further. The particles of matter (atoms or parmanu)
normally exist in a combined form. This combined form of atoms is now called ‘molecules’. All matter is made up of
small particles called atoms and molecules. Different kinds of atoms and molecules have different properties due to
which different kinds of matter also show different properties.
Laws of Chemical Combination
The laws of chemical combination played a significant role in the development of Dalton’s atomic theory of matter.
There are two important laws of chemical combination.
(A) Law of conservation of mass
* Law of conservation of mass was given by Lavoisier in 1774. According to the law of conservation of mass :
Matter is neither created nor destroyed in a chemical reaction. The substances which combine together in a
chemical reaction are known as ‘reactants’ whereas the new substances formed as a result of chemical reaction
are called ‘products’. The law of conservation of mass means that in a chemical reaction, the total mass of products
is equal to the total mass of reactants. There is no change in mass during a chemical reaction.
Ex. Lavoisier showed that when mercuric oxide was heated, it produced free mercury and oxygen. The sum of masses of mercury and oxygen was found to be equal to the mass of mercuric oxide
Mercuric oxide = Mercury + Oxygen
100 g 92.6 g 7.4 g
Sol. Mass of the reactant = 100 g
Mass of the products = 92.6 + 7.4 g = 100.0 g
= 100 g
Since the total mass of the products formed is equal to the total mass of the reactants undergoing reaction, so the data is in agreement with low of conservation of mass.
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Science Class 9 Exam Resources: Chapter 3 Atoms and Molecules
Comprehensive Study Resources for Chapter 3 Atoms and Molecules
Access all crucial study resources for Chapter 3 Atoms and Molecules conveniently on this page. Our curated archive features in-depth notes, visual Mind Maps for rapid review, and targeted Sure Shot Questions likely to appear in upcoming CBSE exams. Developed strictly around the current 2026 curriculum for Class 9 Science, these tools are recommended by expert educators for daily use to accelerate learning.
Expert-Crafted Notes & Previous Questions
Our teachers have used the latest official NCERT book for Class 9 Science to prepare these study material. We have included previous year examination questions and also step-by-step solutions to help you understand the marking scheme too. After reading the above chapter notes and solved questions also solve the practice problems and then compare your work with our NCERT solutions for Class 9 Science.
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FAQs
Our advanced study package for Chapter 3 Atoms and Molecules includes detailed concepts, diagrams, Mind Maps, and explanation of complex topics to ensure Class 9 students learn as per syllabus for 2026 exams.
The Mind Maps provided for Chapter 3 Atoms and Molecules act as visual anchors which will help faster recall during high-pressure exams.
Yes, teachers use our Class 9 Science resources for lesson planning as they are in simple language and have lot of solved examples.
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Yes, our subject matter experts have updated the Chapter 3 Atoms and Molecules material to align with the rationalized NCERT textbooks and have removed deleted topics and added new competency-based questions.