CBSE Class 9 Science Chapter 3 - Atoms and Molecules Class 9 Notes

Atoms and Molecules CBSE Class 9 Revision Notes

Atoms and Molecules Class 9 Notes- This is the 3rd chapter of class 9th Science. Furthermore, in this chapter, we have learned that during a chemical reaction the mass of reactants and products remains unchanged. Moreover, this is known as the law of conservation of mass. Furthermore, the law of definite proportions states that in a pure chemical compound, elements are always present in definite proportions by mass. In addition, the atom is the smallest particle that cannot exist freely. Besides, a molecule is the smallest particle of an element or compound that can exist independently.

Besides, the chemical formula of a compound shows its components elements and number of atoms. In addition, ions are a cluster of atoms. Also, cations are positively charged ions and anions are negatively charged ions. Furthermore, the chemical formula of a molecular compound is determined by the valency of each element.

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Sub-topics covered under Atoms and Molecules

What is An Atom? How Do Atoms Exist? – The topic defines atoms and the way they exist naturally.
What is an Ion? – This topic describes ions, their types, and their properties.
Atomic Mass – The topic overviews the property of atom which is atomic mass.
Molecules and Molecules of Elements – This topic outlines molecules and elements of molecules.
Molecular Mass and Mole Concept – The topic defines molecular mass and what is a mole.
Formulae of Simple Compounds – This topic overviews the formula of the simple compound.
Introduction and Laws of Chemical Combination – The topic outlines the law of chemical combination and its introduction.
Writing Chemical Formula – This topic teaches the way to write chemical formulas.
What are the Modern Day Symbols of Atoms of Different Elements? – The topic highlights the symbols of different elements in modern-day.