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400
Democritus
Democritus proposed that matter is made up of small unbreakable particles. All matter consists of invisible particles callled atoms. Atoms are also a homogenous mixture and are also solid but invisible at the same time. Atoms also differ in size, shape, mass, position, and arrangment. -
400
Aristotle
Aristotle stated that all substances are made up of the 4 elements, Air, Fire, Earth, and Water. He was a very famous phylophiser and a scientist. He also identified close to 600 new species of life. He is also regarded by many as the most intellegent man to ever walk on the planet. -
John Dalton
John transformed Democrius's ideas on atoms into a modern atomic model. All matter is made up of tiny microscropic particles called atoms. The atoms of the same element are identical those of diffrent elements are different. Atoms of diffrent elements combine in small, whole number ratios to form compounds. Chemical reactions involve the combinations of atoms. -
J.J. Thompson
J.J. Thompson discovered the electrons and conducted the Cathode Ray Tube experiment. In the Cathode Ray Tube experiment, if you add an electric charge he found that the moving pieces were negative opposites. He also made the Plum pudding displays electrons embeled in a sphere of positive material. -
Robert Millikman
The major contribution that Robert Millkman made was that he determined the mass and charge of the electron in the atom. He had also conducted The Oil Drop Experiment by mesuring the effect of an electric field on very small oil droplets. From the mass of the drop and the charge on the plates, he calculated the charge on a electron. -
Ernest Rutherford
Rutherford's most major contribution was discovering the nucleas of an atom and made a experiment called The Gold Foil Experiment. He made two conclusions from this experiment which are that the nucleas is made up of mostly positive charge and mass and the atom contains a positive piece in the center. -
Neils Bohr
Neils Bohr had proposed that an electron is found only in specific circular paths, or orbit around the nucleas. His model demonstrated that is model reffered to as a planetory model because electrons move around the nucleas like planets around the sun in a solar system inside a atom. -
Sir James Chadwick
He had confirmed the existence of the neutron inside the nucleas of the atom. Some facts about his discovery is that the electron is mostly all space and the atom consists of 3 regions, The K, The L, The M shell. Also, the nucleas in the center contains Protons and neutrons.