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460 BCE
Democritus
Democritus was a Greek philosopher who proposed the idea that matter is made of tiny, indivisible particles, which he called atoms. He did not have the equipment to test his ideas by using controlled experiments, and his ideas were eventually rejected. https://www.youtube.com/watch?v=TgWn91ap99A -
John Dalton
John Dalton was an English chemist. His ideas from the atomic theory of matter. His ideas were all elements are composed (made up) of atoms, all atoms of the same elements are alike, atoms of different elements are different , and atoms of different elements combine to from compound. -
J.J. Thompson
J.J. Thompson was an English scientist. He discovered the electron when he was experimenting with gas discharge tubes, he noticed there was a movement in a tube and called the movement cathode rays. Those rays moved from the negative end of the tube to the positive end, then he realized that the rays were made of negatively charged particles- electrons. https://www.youtube.com/watch?v=X2uvuSThtuI -
Lord Ernest Rutherford
Ernest Rutherford created a famous experiment called foil experiment, he used a thin sheet of gold foil, also yours a special equipment to shoot alpha particles at the gold foil. Most of the particles passed straight through the foil, some particles went straight back or went in another direction. https://www.youtube.com/watch?v=5pZj0u_XMbc -
Niels Bohr
Niels Bohr was a Danish physicist. He proposed a model of the atom that is similar to the model of the solar system, the electrons go around the nucleus like planets orbit around the sun. All electrons have their levels, a certain distance from the nucleus. Each energy level can hold a certain number of electrons. https://www.youtube.com/watch?v=t005KSfs03g
