Uncovering the secrets of the atom

In the last section we saw how the idea of the atom grew over time. However, science is made by a never-ending stream of curious people who attempt to learn ever more about the world around us. The experiments had only just begun and the end of the of the 1800s saw experiments that began to get inside the atom.

Cathode Ray Tube Experiments

Towards the end of the 1800s a lot of research attention was directed at radiation. Physicists were trying to discover how energy could be transmitted through empty space. During this period a lot of work had been done with electromagnetic radiation; x-rays, ultraviolet, radio and infrared. One piece of equipment that a lot of scientists at the time were using in this quest was a sealed glass tube. Inside this tube was a vacuum and some electrodes which went through the glass. One of the inside walls of the tube was often coated with a chemical which was phosphorescent, i.e. the One problem with conducting such experiments in normal air is that the individual particles of gas can get in the way. So, to get around this a piece of lab equipment was produced. The design of the equipment featured a glass tube with all the air inside removed to become a vacuum. Through the glass wall

Through his work with the cathode ray tube, J.J. Thomson found that what was traveling through the air actually had a mass; it was a form of matter. It was not, as had been thought, an electromagnetic wave. There was some kind of particle which carried a negative charge through the air. However, this particle was far to small to be an atom. In fact, Thomson managed to carry out experiments that showed that the mass of the particle was about 1800 times smaller than that of a hydrogen atom. From this discovery, he proposed that the atom was not in fact the smallest known particle, but that his newly discovered "corpuscle" was even smaller than an atom.

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