Explore the fascinating world inside an atom with these easy-to-understand Class 9 Science revision notes. This complete guide covers subatomic particles, Thomson’s and Rutherford’s models, Bohr’s model, electronic configuration, atomic number, mass number, isotopes, isobars, valency and ions.Designed for quick revision, exam preparation and better understanding, with clear explanations, important points, examples and comparison tables.Perfect for Class 9 students who want to revise the complete chapter in a simple and organized way!