The next question was "How were they arranged in the atom?" Thompson knew that the atom overall had a neutral charge, so he imagined that the negatively charged electrons must be distributed randomly in a positively charged matrix. He called them "corpuscles " we call them "electrons." So even though we didn't understand what shapes they took, we knew that there were both negative and positive components to matter. He concluded that the cathode "rays" weren't rays or waves at all, but were, in fact, very light, very small negatively-charged particles. And the mass was about a thousand times lighter than a hydrogen, which was the smallest bit of matter known at the time. Thompson took the discharge tube research further: by measuring how much heat the cathode rays generated and how much they could be bent by magnets and other things, he was able to estimate the mass of the rays. Goldstein didn't fully understand what he'd discovered here- I mean, scientists still hadn't figured out what was responsible for the negative charge in the rays either. But in 1886, German physicist Eugen Goldstein found that the tubes also emitted light from the positive electrode- basically, a ray headed in the opposite direction, which meant that there must also be a positive charge in matter. Because this light was originally produced by a negative electrode, or cathode, it was called a cathode ray, and it had a negative charge. In the 1870s, scientists began probing what stuff was made of using discharge tubes, basically gas-filled tubes with electrodes in each end, which emit light when an electrical current passes through them- basically, what a neon light is. The next logical question was "Why? Why do they behave the way they do?" This led to the investigation of atomic structure. Thanks to these, and other great minds, by the eighteen hundreds we had a better grip on the general behavior of atoms. We've been talking a lot about the fine details of chemistry in recent weeks, and we're gonna keep doing that as we move on to nuclear chemistry and then to the basics of organic chemistry, but we do, I wanted to set aside some time to explain how we know what we know about the atom today, and how we know that we're not quite done figuring it out. But, as has been the case in all science, each scientist built on what had been learned before. As time went on, many more were the result of rigorous experimentation. Some models, like that of Leucippus, were just blind guesses. Now this makes a certain amount of sense if you don't happen to have access to electron microscopes or cathode-ray tubes or the work of generations of previous scientists, cause the fact is atomic theory as we know it today is the product of hundreds, if not thousands, of different insights. So, they thought that iron atoms were hard and stuck together with hooks, clay atoms were softer and attached by ball and socket joints that made them flexible, and cheese atoms were squishy and delicious. And they attributed properties of each substance to the forms of the atoms. So basically, they thought that iron was made up of iron particles and clay was made up of clay particles and cheese was made up of cheese particles. They gave these particles the name " atomos," which means uncuttable or indivisible. No one knows how they developed this concept, but they didn't think the particles were particularly special- they just thought that if you cut something in half enough times, eventually you'll reach a particle that can't be cut anymore. That's when Greek philosopher Leucippus and his pupil Democritus first came up with the idea that matter is composed of tiny particles. How do you picture an atom in your mind- like this, or like this, or maybe one of these? If you understand enough about atoms to visualize any of those things, then you know more about atomic theory than scientists did just a hundred years ago, and, like, WAY more than they thought they knew twenty-five hundred years ago. Want to find Crash Course elsewhere on the internet? Leucippus, Democritus & Atomic Theory 0:09 From Leucippus to Heisenberg to you - yes, YOU - the story of Atomic Chemistry is all wibbly-wobbly. How did we get here? Well, in terms of Atomic Chemistry, Hank takes us on a tour of the folks that were part of the long chain of other folks who helped us get to these deeper understandings of the world. Also, if you can afford to pay a little every month, it really helps us to continue producing great content. You can directly support Crash Course at Subscribe for as little as $0 to keep up with everything we're doing.
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