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330
Aristotle described the four causes
- Material cause saying what stuff is made from
- Efficient the maker of things
- Formal which is pattern
- Purpose that something is made
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430
Empedocles' philosophy
The world is due to the mixing of separation of four parts earth, air, fire, water, which he called "roots", and the blending and separation of elements (love and strife). -
430
Plato identified each element with a regular solid
Fire= tetrahedron, air= octahedron, water= icosahedron, and earth= cube. -
450
Democritus and Leucippus discovered the world consists of atoms
Didn't believe the hypothesis that "everything is one" so they dug deeper and discovered that the world essentially consists of myriads of tiny, indivisible particles. -
Period: to
The American Revolution
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Period: to
George Washington President
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John Dalton's atomic theory
All elements are composed of tiny particles called atoms, atoms of the same element are identical but the atoms of different elements are all different, atoms of different elements can physically mix together or can chemically combine in simple whole-number ratios to form compounds, and chemical reactions occur with the gain, loss, or rearrangement of atoms, but chemical reations never lead to the changing of an atom into another element. -
John Dalton discovered the law of multiple proportions
Whenever two elements for more than one compound, the different masses of one element that combine with the same mass of the element are in the ration of small, whole numbers -
Nagoaka developed the Saturnian Model
Based his model of the atom around the rings of the planet Saturn, turned out to be wrong. -
Robert Millikan discovered negative charge of electrons
Used the oil-drop method; determined charge of oil drops when held at equilibrium. -
Lord Ernest Rutherford's "The Gold Foil Experiment"
Tested J.J. Thompson's plum pudding model by shooting energetic alpha particles at foil. Created the Rutherford model. -
Period: to
World War I
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Erwin Schrodinger published his quantum mechanical model equation
Mathematically explains the properties of electrons. -
Max Planck won the Nobel Prize in physics for his discovery of "Planck's Constant"
A constant that reflects the physical size of energy in quanta. -
Niels Bohr wins the Nobel Prize for his atomic model
Electrons located on different energy levels that were fixed at different distances from the nucleus. -
Werner Heisenberg published theory of quantum mechanics
The mathematical description of the movement of subatomic particles. -
Louis de Broglie's quantum theory is confirmed
Electrons can act like waves or particles -
Sir James Chadwick wins the Nobel Prize for Physics for his discovery of the neutron
Lead to the fissioning of Uranium-235 which lead to the atomic bomb. -
Period: to
World War II
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John F. Kennedy Shot
