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400
Democritus' Major Contribution
Democritus pruposed the existance of atoms. He created a model of an atom but did not have advanced parts labled like nuetrons or electrons or the nucleus. -
400
Aristotle's Major Cotribution
Aristotle took Democritus' ideas further by ceating another atomic model. He concluded that the world is made of four elements that can be in various tempetures. The elements are:
1. Earth
2.Air
3.Water
4.Fire -
John Dalton's Major Contribution
John Dalton transformed Democritus' and Aristotle's ideas into a scientific model. He brought up the concept of neutrons, protons, electrons and the nucleus. -
J.J. Thomson's Major Contribution
J.J. Thomson was a very bright minded scientist. He conducted the Cathode Ray Tube experiment. By conducting the exeriment, he found out that neutrons, protons, and electrons have positive, negative, and neutral charges. He ceated the Plum Pudding Model that showed the charges of the parts of the atom. -
Robert Millikan's Major Contribution
Robert Millikan conducted the Oil Droplet Experiment. He attemped to measure the charge of protons, neutrons, and electrons. He took J.J. Thomson's work further. -
Ernest Rutherford's Major Contribution
Ernest Rutherford conducted the golden foil experiment. It was all related to the mass of the atom. He concluded that 99% of the mass of the atom is from the nucleas. -
Neils Bohr's Major Contribution
People hadn't known that electrons orbit around the neucleas and there are three rings of them. Neils Bohr discovered that the electrons orbit the neucleas and there are three rings of them. While explaining, he stated that electrons move around the nucleas like planets. -
Sir James Chadwick's Major Contribution
At last, Sir James Chadwick perfected the atomic model and made it the current modern view one.
