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Democritus
Democritus was a Greek philosopher who suggested the concept that matter is composed of invisible-like, singular, hard particles he called "atomos," that then went to the English word "atom," which meant indivisible. He was not able to prove his ideas without the proper equipment and so forth, his ideas got rejected by new revisions by newer scientists with newer ideas. [https://www.youtube.com/watch?v=RvuaZ6EEUgs] (video ends at 2:53) -
John Dalton
John Dalton had an atomic model similar to Democritus's atomic model. His model showed that atoms were like smooth, round balls that cannot be broken down. His theory thought that all elements are made of atoms that can't be divided, all atoms of the same elements are alike, atoms of different elements are different, and that atoms of different elements can combine to form compounds made of two or more elements in a fixed ratio. All of these generalizations led to his simple atomic model. -
J.J. Thompson
J. J. Thompson was an English scientist that discovered a new particle in atoms: the electron. Electrons have negative charges that in his atomic model, were attracted to the positive parts, the protons. In his model, all electrons were on a big proton that represented his atom. He discovered the electron when he was experimenting with gas discharge tubes. He discovered cathode rays as a movement that were made of negatively charged particles known as electrons. -
Lord Ernest Rutherford
Rutherford's atomic model came from one of the most famous experiments in history: The Gold Foil Experiment! The experiment used a positively charged source and shot it at a skinny, gold foil. Some particles went through, while others got deflected. With his team of scientists and researchers, Rutherford and his team inferred from his experiment two things. One, atoms have a small positive nucleus and two, atoms mostly have empty space. These generalizations led to their atomic model. -
Niels Bohr
Niels Bohr, a Danish physicist, made the closest atomic model to the one we use today. He proposed that the particles in atoms revolve around the nucleus, from Rutherford's idea. His atomic model had electrons orbiting the nucleus like the earth orbits the Sun. Bohr's model was called the "Planetary Model,' since it related to the way planets orbit the Sun and so on. Bohr also found out about that the rings of atoms can hold a certain amount of electrons, or energy levels.
