Atomic Theory

Front 1

Aristotle believed that all matter is indivisible and...

Back 1

Different materials are the result of moisture, dryness, heat, and cold

Front 2

Democritus stated that all mater is made of

Back 2

Tiny particles and empty space

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Two-class system

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Philosophers don't use their hands, workers don't use their mind

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The Alchemists tried to make gold out of common materials and established...

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A system of experimental techniques, systems of notations, and symbols

Front 5

Sir Isaac Newton and Robert Boyle challenged

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Aristotle's views on matter

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Antoine LaVoisier

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Established Law of Conservation of Matter

Front 7

Joseph Proust

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Established Law of Definite Proportions which say that elements join in specific ratios to form compounds

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John Dalton

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Law of Multiple Proportions

Front 9

John Dalton's 4 assumptions about matter

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1. All matter is made of atoms

2. Atoms of the same elements are identical

3. Atoms if different elements are not alike

4. Atoms untie in simple ratios to form compounds

Front 10

2 flaws in Dalton's atomic theory

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1. "Atoms" is a misnomer because atoms are not divisible

2. Atoms of the same elements are NOT identical. Each element had 2+ isotopes which have the same # if protons, different # of neutrons

Front 11

J.J. Thomson

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Experimented with cathode rays and magnetic fields. He found it rays were made of particles he called corpuscles (electrons)

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Robert Millikan 1909

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Experimented with oil, gravity and electrostatic charges with the droplets hovering. The charges n the droplets were different but they could be reduced to the same common denominator. Gave us charge and mass of an electron

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Lord Ernest Rutherford 1911

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Bombarded gold foil with alpha particles and concluded that atoms are mostly empty space

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Henry Mosley 1914

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When generating x-rays, different metals produced different wavelengths. Concluded that each element has its own # of protons in its nucleus and established atomic number

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Walther Bothell 1930 & James Chadwick 1932

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Alpha particles to dislodge a mysterious particle (neutrons) from a piece of Beryllium metal. They were directed at a piece of wax and they displaced protons.