An electron is a negatively charged subatomic particle represented by the symbol e-. The mass of an electron is only 1/1836 that of a proton.
Electrons were discovered by J. J. Thomson in 1897. He was studying the properties of cathode rays. Thomson constructed a glass tube from which much of the air was pumped out and then he applied a high electrical voltage between two electrodes at either end of the tube.
He detected that a stream of particles (ray) was coming out from the negatively charged electrode (cathode) to the positively charged electrode (anode). This ray was called cathode ray. He proved that these cathode rays could be deflected, or bent, which meant that they were made of small particles. He named these particles ‘corpuscles.’ Thomson initially underestimated the relevance of his discovery. He had assumed that it was too insignificant to be of importance to those outside a lab. However, the magnitude of this discovery was soon realised. The name ‘electron,’ advocated by G. F. Fitzgerald, J. Larmor, and H. A. Lorenz was adopted by the scientific community.
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