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500
Democritus
- ( Couldn't find the exact date) -This theory is the idea that matter is made up of little units called atoms.
- Later on, this theory was confirmed that atoms are in fact, made up of smaller particles.
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Antoine Lavoisier, The Law of Conservation of Mass
- (Couldn't find exact date when the law was created)
- Discovered by Antoine Lavoisier ( Aug. 26, 1743-May 8, 1794).
- This law states that mas is neither created nor destroyed in chemical reactions.
- In other words, the mass of any element at the begining of a reaction will equal the mass of that element at the end of the reaction
- The finding of this law revolutionized science.
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Joseph Proust, The Law of Definite Proportions
- (Couldn't find exact date) -Joseph Prouat ( Sept. 26,1754-July 5, 1826)
- This law states that a chemical compound always contains exactly the same proportions of elements by mass. -Proust made this obsrvation or discovery from experiments.
- He made a statement which was, " Iron like many other metals is subject to law of nature which presides at every true combination, that is to say, that it unites with two constant proportions of oxygen. It does not differ form almost any known combustible
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John Dalton, Solid Sphere Model
-( Couldn't find exact date)
- John Dalton ( Sept. 6, 1766-July 27, 1844)
- atoms are seen as solid, indestructable spheres
- Model explains a lot of chemical propeeties
- Model confirms the basic laws of chemistry; conservation of mass and definite proportions -
J. J. Thomson, Electron
- ( Couldn't find Exact date) -J.J. thomson ( Dec 18, 1856-Aug 30, 1940 )
- The electron is a subatomic particle with a negative charge
- No two electrons can occupy the same quatum state
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J. J. Thomson, Cathode Ray Experiment
- ( Couldn't find exact date)
- the dicovery of the electron was the result of this experiment
- Also, this experiment showed that elsctons comprising cathode rays were nearly 2,000 times smaller in mass than the lightest known particle
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Max Planck, Quantum Theory
- (Couldn't find the exact date). -Max Planck (April 23, 1858-Oct 4,1947)
- This theory explains the natured behavior of matter and energy on the atom and subatomic level
- He found that energy exists in individual units in the same way that matter does and therfore, its quantible
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J. J. Thomson, Plum Pudding Model
- (Couldn't find exact Date)
- in this model, the atom is composed of electrons surrounded by a soup of positive charge to balance the electron's negative charge
- electrons were free to rotate in a ring
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Ernest Rutherford and Hans Gerger, Gold Foil Experiment
- (Couldn't find exact date)
- Rutherford ( Aug 30, 1871-Oct 19, 1937)
- Gerger ( Sept 30,1882-sept 24, 1945)
- Experiment was to determine the layout of an atom
- Determined this by using bombarding gold foil with alpha particles while in a dark room
- Watched for tiny flashes as the scattered particles hit the screen
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Ernest Rutherford, Nuclear Model
- (couldn't find exact date)
- Model shows or statesthat the atom consists of a dense positive center called the nucleus and is orbitted by electrons
- This model closed the alpha particle experiment
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Ernest Rutherford, Nucleus
- (Couldnt find exact date)
- the nucleus is the very dense region consisting of protons and neutrons that are later discovered
- the nucleus is located at the center of the atom
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Niels Bohr, Bohr Model
- (couldn't find exact date)
- Niels Bohr (Oct 7, 1885-Nov 18, 1962)
- this model is the modification of the rutherford model -the model is a planetary model in which the electrons orbit around the atomic nucleus
- electrons orbit the nucleus in orbits that have a set size and energy
- the energy of the orbit is related to its size
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Ernest Rutherford, Neutrons
- (couldnt find the exact date)
- the neutron is a subatomic particle with no electric charge
- the number of neutrons can determine the isotope of an element
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Ernest Rutherford, Protons
- (couldnt find the exact date)
- a proton is a subatomic particle that has a positve charge
- one or more protons are present in the nucleus
- a proton is also the atom's atomic number
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Louis de Brogile, Quantum Mechanical Model
- (couldnt find the exact date)
- Louis de Brogile ( Aug 15, 1892- March 19, 1987)
- Shows electron beams could be diffracted or bent as they passed through a slit
- the waves produced by an electron confined by its orbit sets up a standing wave , energy, and frequency
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Warner Heisenberg, Uncertainty Principle
- (Couldn't find the exact date)
- Warner Heisenberg ( Dec 5, 1901-Feb 1, 1976)
- Principle states that the more precisely you know the position of a particle, the less precisely you can simulataneously know the momentum of that same particle
