Study Material IX Science Ch-3- Atoms and Molecules
The word atom is derived from the Greek word “Atomos” which means indivisible. John Dalton modeled atoms as hard indivisible spheres. An Indian philosopher Maharishi Kanad, postulated that if we go on dividing matter ( padarth ), we shall get smaller and smaller particles. Ultimately, a time will come when we shall come across the smallest particles beyond which further division will not be possible. He named these particles Parmanu . Ancient Greek philosophers – Democritus and Leucippus suggested that if we go on dividing matter, a stage will come when particles obtained cannot be divided further. Democritus called these indivisible particles atoms (meaning indivisible). How and why elements combine and what happens when they combine. Antoine L. Lavoisier laid the foundation of chemical sciences by establishing two important laws of chemical combination. (a) The Law of conservation of mass was stated by Antoine L. Lavoisier as” Mass can neither be created nor destroye...