Answer
The electron was discovered by J.J. Thomson during an experiment showing the conduction of electricity through gases.
Work Step by Step
Joseph John Thomson conducted an experiment to show the conduction of electricity through gases. He discovered that the cathode rays were actually the beam of negatively charged particles that traveled from cathode to anode. This was how the electron was discovered. The basic property of electrons discovered was that they are negatively charged low-mass particles present inside an atom.
