Hi! I’m Atom and I make up everything! I’m so small that I’m invisible to the naked eye. Well, except for this comic strip. But do you know that there’s even smaller particles that make up an atom like me? We’ll need to start from thousands of years ago, during the ancient Greek era.
The Greek philosopher Democritus was the first one to propose the idea of my existence. He said that if you cut something into parts, it’ll get so small that it won’t be divisible anymore. He called this “Atomos”, which is Greek for “indivisible”. Yes, that’s where I got my name! He created the first atomic model. It was simply a round sphere.
Many years later, an English chemist and physicist, John Dalton, proposed that I make up all matter and that I can’t be divided. He said we’re indestructible and looked like a solid ball.
Then an English physicist, J.J. Thomson conducted an experiment using cathode rays. His research proved the existence of negatively charged particles, later called electrons. He concluded that atoms were made up of electrons, and formed the “Plum Pudding” atomic model, where atoms appear as if they’re made up of really small electrons.
German physicist Eugen Goldstein also conducted experiments by observing a beam of light, as it passes through a discharge tube. He then proved that atoms were made up of different particles, not just electrons.
Ernest Rutherford, another physicist, shot a beam of alpha particles onto a piece of really, really thin gold foil. With this experiment, he discovered protons, and the atomic nucleus. He also concluded that these particles orbit the nucleus, like our solar system.
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