Philipp Lenard
Lenard saw that the absorption of cathode rays was proportional to the density of the material they passed through. This was opposite to the idea that they were some sort of electromagnetic radiation. He also showed that the rays could pass through the air and appeared to be scattered by it. This meant that they must be particles that were even smaller than the molecules in air. He confirmed some of J.J. Thomson's work, and this showed that cathode rays were streams of negatively charged energetic particles. He called them quanta of electricity or for short quanta, after Helmholtz. J.J. Thomson had called them corpuscles, but electrons became the everyday term. Lenard used this knowledge, together with the results of his and others' earlier experiments on the absorption of the rays in metals. He showed that electrons were parts of the atom. Lenard worked out that atoms were mostly empty space. He said that every atom consists of empty space and electrically neutral corpuscules called "dynamids", each consisting of an electron and an equal positive charge.