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322
Aristotle
Date is BC
Aristotle believed that all objects were composed of potential and reality, Aristotle didnt think atoms could be constantly moving if they were in a void. He beleived there were four elements and four qualities, and that they would align into their rightful place and be at rest. -
346
Plato
Date is BC
Plato thought that there were four elements; Earth, Fire, Water, and Air. He got that idea from Empedocles. He thought that earth was a cube, fire was a tetrahedron, water was a icosahedron, and air was a octahedron. -
370
Democritus
Date is BC
Democritus developed atomism to say that atoms were solid bodies that were infinite in number. He thought that if you continued to cut an object in half you would eventually reach an uncuttable peice. -
420
Luecippus
Luecippus thought that there were two different elements; the "full" or "solid" and the "empty" or "void". He thought that an infinite number of atoms exist and are responisble for the special properties of matter. -
432
Empedocles
Empedocles believed that all things were made of either earth, fire, water, or air. He also thought that light traveled at a finite velocity. -
Max Planck
Max Planck created Plancks Constant which is (h)= 6.626x10^-34 (proportion of energy and frequency of electromagnetic waves)E=hv -
Period: to
Atomic Theory Timeline
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JJ Thomson
Thomson suggested that an atom was a sphere of positive matter with electons sprinkled throughout. -
Hantaro Nagaoka
Nagaoka created the saturnian atomic model. -
Robert Millikans Oil Drop
Millikan created the oil drop experiment to measure the charge of an electron. To start the experiment Millikan sprayed oil mist in to a chamber and let them fall until they reached terminal velocity so he could calculate the mass of the drops. Next he shot x-rays at the drops to give them a charge. The charge made electrons attach to the drops. Then a positivly charged plate was ajusted to make the drops float, once the drops floated then Millikan knew the charge on an electron. -
Ernest Rutherford
Rutherford discovered the atomic nuecleus. He also created the planetary atomic model. He also claimed that radioactive elements have half lives. -
Neils Bohr
Bohr created the Bohr model based on his belief that electron were located on different levels based on the amount of energy they had. -
Erwin Schrodinger Wave Equation
Studied the theory of Louis de Broglie and published his quantum mechanical model, or wave equation. It is based on the quantum theory which states that matter has properties associated with waves. -
James Chadwick Discovers Nuetron
James Chadwick discovered the nuetron by smashing alpha particles into beryllium. This released radiation that was aimed into some wax. When Chadwick sudied the wax he found big nuetral particles.
