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440
Democritus
He discovered the atom. He thought that it could not be divided. He thought the atoms were small hard particles of different shapes and sizes. -
Period: 440 to
Atomic Theory
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Dalton
He belioved that atoms were small particles that could not be created, divided or destroyed. Also that atoms with the same element are exactly alike and atoms with different elements are different. He also believed that atoms could be joined with other atoms to make a new substance. His model of the atom or what he thought it would look like was a solid sphere. -
Thomson
He belived that atoms had small particles inside of the atoms. He experimented with a cathode-ray. He found that the positively charged plate attracted the beam. He concluded that the beam had negatively charged particles that are in every atom. He called these charges electrons. His model of the atom was called the "Plum Pudding Model." His model had the electrons mixed inside of the atom. -
Rutherford
He desigened an expieriment to test Thomson's theory. He aimed a beam of small, positively charged particles at a thin sheet of gold foil. He could see where the particles hit. He expected the to pass through the gold, which some did. Others deflected or bounced straight back. Rutherford thought the center of an atom had a positively charged nucleus. His model had a nucleus in the middle and electrons spinning on the outside. -
Boher
He belived that the electrons moved around the nucleus in ceartain patterns. In his there are no paths between the levels, but electrons can jump from a path in one level to a path in another level. -
Schrödinger and Heisenberg
They better explained the electrons in an atom. They belived that the elcetrons didn't travel in specific paths. They said the electron could not be predicted. The electrons could be found in electron clouds. These electron clouds surounded the nucleus. -
Chadwick
He belived that the proton and the electrons did not make up the atomic mass so ther had to be something else. He tried expierments to try and find a neutral paricle that had the same mass as the proton. He foundthat he had suceeded in discovering the neutron. -
Heisenberg
He helped discover that electrons do not travel in orbits. Also that all electrons coatain photons that change the momentuem and physics. He also calcculated the behavior of elctrons. The electron cloud was surrounding the nucleus and all the electrons were widley spread out.
