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Democitus
He considered that matter is made of tiny, invisible, indestructible, particles that he called atoms. He did not have the correct and necessary equipment to test his ideas, so later on his ideas were rejected.
https://www.youtube.com/watch?v=TgWn91ap99A -
John Dalton
Even though he was color blind and could only see the color yellow, he still worked hard. He believed all elements are composed of atoms and is impossible to divide. Atoms are all alike. When atoms combine they have to be a definite whole number ratio. An example is water, it has 2 hydrogen's and 1 oxygen so the ratio is 2:1. After doing a lot of work he found out that chemical combinations happen between two particle with different atomic weights.
https://www.youtube.com/watch?v=wsYDL6EjV4k -
J.J. Thompson
He found the electron experimenting with gas tubes. When he saw a movement he called it the cathode rays. The rays moved from end to end. He was experimenting with gas discharged tubes when he discovered the cathode rays.Then he realized they were electrons. He even designed instruments that passed cathode rays through the metal parts. He also proved that the presence of isotopes is in a non-radioactive element.
https://www.youtube.com/watch?v=JwdGFZA3WOs -
Lord Ernest Rutherford
He made the gold foil experiment. He used special equipment and a sheet of gold foil. He shot alpha particles at the gold foil. Some particles went straight through the foil, others bounced off. His experiment ended up showing that atoms are made of positive nucleus that pushes away positive alpha particles. Also that particles are basically empty space. Because of this he is believed to be the only Nobel prize winner recipient. https://www.youtube.com/watch?v=Zd6_zVdMgJk -
Niels Bohr
His model looked like the solar system. IT looked like the solar system because his electrons went around the rings like planets do around the sun. Each electron had a certain energy level that had a certain distance from the nucleus. Each energy level had a certain number of electrons. Level one can hold two electrons, level two: 8, level 3: 18, and level 4: 32. The energy of the electrons go up as you get to the other levels.
https://www.youtube.com/watch?v=Cn6v5ygyZHQ
