Revision notes for class 9 science chapter 3 atoms and molecules is provided here to help students revise the chapter. Revision is one of the most important parts of studies. Revising the chapter help students to recollect whatever they have learned from that chapter. The chapter atoms and molecules is aimed to teach students about the laws of chemical combinations which are the law of mass and low of constant proportions. Along with the laws, the students will also be taught about an atom, a molecule, how to write chemical formulas and mole concepts.