J.J. Thomson was able to demonstrate that the electron was a universal component of matter. He changed the gas components of the cathode ray tube and measured the charge to mass ratio (e/m) with each experimental setup. Regardless of the identity of the gas, he arrived at the same charge to mass ratio. He concluded that the electron must be found in the atoms of every element in nature.
This discovery went against the postulates of Dalton's atomic theory. If you recall, Dalton stated that atoms are indestructable, meaning that there are no particles smaller than the atom. However, Thomson's cathode ray experiment demonstrated that there are particles smaller than the atom. These particles are referred to as subatomic particles.
Luckily for Thomson, other experiments conducted around the same time supported his experimental results of the charge to mass ratio. His calculations suggested that the electron was over a thousand times smaller in mass compared to the entire atom!
