What does an atom look like? How did scientists figure out what it looks like? Truemper 2016
Atomic Theory Truemper 2016
Democritus Smallest piece of all matter is not divisible He named the smallest piece of matter “atomos,” meaning “not to be cut.” Truemper 2016
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John Dalton 1760-1844 Father of Modern Atomic Theory matter is made of atoms atoms in an element are identical different elements have different atoms atoms maintain their mass even in a chemical reaction Truemper 2016
J.J. Thomson 1897 Truemper 2016
When a magnet was placed near the beam of light, it separated into two parts Truemper 2016
When a magnet was placed near the beam of light, it separated into two parts Truemper 2016
Thomson Model Where did they come from? This surprised Thomson, because the atoms of the gas were uncharged. Where had the negative charges come from? Truemper 2016
Thomson Model Proposed a model of the atom that is sometimes called the “Plum Pudding” model. a sphere with negatively charged electrons scattered. Truemper 2016
J.J. Thomson 1897 Hear Thomson talk the Electron discovered electrons (charged particles) Truemper 2016
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Rutherford 1911 Using atoms to see what is inside of other atoms Truemper 2016
Rutherford Truemper 2016
Rutherford Experiment Molecular Expressions Truemper 2016
Rutherford’s experiment: Discovery of the Nucleus Most of positively charged particles Rutherford shot at the gold foil passed right through without changing course at all. However, some did bounce away from the gold sheet as if they had hit something solid. He knew that positive charges repel positive charges. Rutherford found the Nucleus Truemper 2016
Rutherford’s model A nucleus in the center, with electrons moving around in the open space Truemper 2016
1) Most of the volume of the atom is ... empty space Truemper 2016
2) Virtually all mass atom found in ... ... the nucleus Truemper 2016
3) Strong, positive charge in the center of atom 3) Strong, positive charge in the center of atom Truemper 2016
Relative Sizes in the Atom Truemper 2016
Did you know ... If the atom were the size of a football stadium, the nucleus would be the size of a.... Truemper 2016
.... a marble!!! Truemper 2016
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Bohr Model Electrons move in definite orbits around the positive nucleus Like the planets orbiting the sun. These orbits, or energy levels, are located at certain distances from the nucleus. Truemper 2016
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Chadwick discovers the nucleus has neutrons Truemper 2016