What are the Characteristics of Electron, Proton and Neutron Electron Electron was discovered by J.J. Thomson. Cathode rays consist of small, negatively charged particles called electrons. The electron is a negatively charged particle found in the atoms of all the elements. The electrons are located outside the nucleus in an atom. An electron is usually represented by the … [Read more...] about What are the Characteristics of Electron, Proton and Neutron