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447
Construction of the Parthenon
447-432 BCE -
460
Democritus's atomic theory
Democritus lived from 460 BC to 370 BC
Democritus's atomic theory:
-said matter could not be divided into smaller pieces forever; eventually the matter would be so small it could not be cut and that smallest piece would be called an atom -
American Independence
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Joseph Proust's Law of Definite Proportions
A compound is composed of exact proportions of elements reguardless of how the compound was created. The ratio of the elements is consistant reguardless of the amount or means by which the compound was created. -
John Dalton's Atomic Theory
Dalton's atomic theory
1. all matter is made of atoms that are both invisible and indestructible (and cannot be made)
2. all atoms of one element are identical
3. compounds are made of two or more different kinds of atoms
4. a chemical reaction is when the atoms rearrange -
Civil War starts in the United States
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Henri Becquerel discovers Radioactivity
-used uranium and photographic plates - when the uranium was left on the plates with no other variables and the plates were developed there was still a clear image on the plates where the uranium was. he also showed that the radiation from uranium could be deflected by a magnetic field proving that the uranium was positively charged -
First Summer Olympics
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JJ Thomson Discoveres the Electron
Discovered the electron while performing a series of experiments to study the nature of electric discharge in a high vacuum cathode-ray bulb. -
Planck's Constant
Max Planck used the idea of quanta to explain hot glowing matter. He explained the pattern of light intensity emitted from a black body at any given frequency. -
JJ Thomson proposed plumb pudding model
proposed the plumb pudding model
-a positively charged atom dotted throughout with negatively charged electrons -
Albert Einstein's theory of relativity
Albert Einstein's discovery of the theory of relativity and mass energy equivalence lead to his invention of the atomic bomb.
Einstein said light energy could only be released in bursts or levels called quanta, and he accurately calculated the average distance an immersed visible particle wo
Albert Einstein did not agree with the quantum model that said that the universe was inherently chaotic. Einstein proved that light acted like a particle, adding to Newton's discovery of light being a wave. -
Robert Millikan'soil drop experiment
Millikan measured the charge on an electron with his oil-drop experiment. -
Teddy Roosevelt takes office
Americas 26 president -
Rutherford directs the Geiger-Marsden ecperiment
this experiment suggested that the plum pudding model from J. J. Thomson of the atom was incorrect. Rutherford's new model for the atom, based on the experimental results, contained the new features of a relatively high central charge concentrated into a very small volume in comparison to the rest of the atom and with this central volume also containing the bulk of the atomic mass of the atom. Rutherford later won the Nobel prize in Chemistry for his discovery -
Titanic Sinks
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Neils Bohr: planetary Model
Neils Bohr proposed the planetary model
-electrons are arranged in concentric circular orbits around the nucleus -
Erwin Schrodinger introduces sub-energy levels
Used mathematical equations to describe likeliness of finding electrons in certain places (quantum mechanical model) , and he introduced the idea of sub-energy levels -
Werner Heisenberg's Uncertainty Principle
Werner Heisenberg's Uncertainty Principle states that the exact location and energy of an electron cannot be determined simultaneously. He determined that by finding one of these two values there was uncertainty in the other. -
James Chadwick discovered the Neutron
James Chadwick discovered the neutron
-struck beryllium atoms with lots of alpha particles
-unknown radiation was produced and this radiation was composed of neutrons (he knew it was a neutrons because there was no charge) -
Invention of Computer
first freely programmable computer -
Opening of the Golden Gate Bridge
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First Dairy Queen
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brown vs board of education
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Louis de Broglie wins Nobel prize
Louis de Broglie won the Nobel prize for his discovery of the wave nature of Electrons -
Aristotle
Aristotle believed in the four elements, earth, water, fire, and air. He thought that no matter how many times you cut a form of matter in half you will always end up with a smaller piece. Aristotle also tutored Alexander the great.
