Structure of the Atom
INTRODUCTION Matter is made up of tiny particles called atoms. Atoms are further made of three fundamental particles or sub тАУ atomic particles called electron, proton and neutron. Earlier Dalton postulated that atom is indivisible i.e. cannot be further divided which proved to be wrong by discovery of sub тАУ atomic particles. Types of Sub - atomic Particles Note - Protons and neutrons are almost of same mass.The mass of proton is approximately 2000 times as that of the electron. Discovery of Sub- atomic Particles (a) Electron (e - ): These negatively charged particles were discovered by J. J. Thomson in 1897. In the experiment, a gas at low pressure was taken in a discharge tube made up of glass. At the ends of the discharge tube two electrodes were placed, connected to a battery for high voltage supply. The electrode connected to the negative end was known as cathode and that to the positive as anode. He then observed a stream of negatively charged particle...