Class 9 NCERT • Science Exploration Series (New Syllabus)
Ch 09: Atomic Foundations of Matter
Select a topic or study module below to explore chemical combination laws, Dalton’s theory, atomic mass units, molecules, chemical formulae via the criss-cross method, molecular mass calculations, bonding basics, and textbook solutions.
Topic 01 • Combination Laws
Understanding Conservation of Mass and Constant Proportions in Chemical Changes
Topic 02 • Dalton’s Theory
Exploring Fundamental Postulates, Indivisibility Principles, and Compound Formations
Topic 03 • What is an Atom?
Defining Atomic Size, Chemical Symbols of Elements, and Modern Atomic Mass Units (u)
Topic 04 • Molecules & Compounds
Differentiating Molecules of Elements and Compounds, Atomicity, and Structures
Topic 05 • Chemical Formulae
Mastering Valency, Ions, and the Criss-Cross Method for Writing Compound Formulae
Topic 06 • Masses & Calculations
Calculating Relative Molecular Masses and Formula Unit Masses with Numerical Practice
Topic 07 • Chemical Bonding
Exploring Ionic and Covalent Bonding Structures via Electron Sharing or Transfer
Module 08 • Solutions & Quiz