William Crookes, J.J. Thomson and the Discovery of the Electron
In 1897, John Joseph Thomson established the existence of "negative corpuscles" present in atoms. He named these tiny particles electrons and stated that they were present in all matter. He subsequently developed a model of the atom involving a sphere of uniformly positive mass with electrons spread throughout. This model became known as the Plum Pudding Model of the atom. In addition, he was able to measure the charge to mass ration (e/m) of the electron.
The History
It was established earlier that passing a high voltage through a confined gas would cause the gas to glow. Sir William Crookes wondered what would happen if the voltage was passed though a tube from which the gas had been removed. His invention, which came to be called a Crookes tube or cathode ray tube, looked like this:
When the experiment was performed, it was seen that the glass itself glowed.
Even more interesting, a shadow of the Maltese cross could be seen at the end of the tube.
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