The Development of Atomic Theory

By: Autumn Arbour

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Who came up with the first theory of atoms? How long ago? What was the theory?

The First theory of atoms was proposed over 2,000 years ago. The theory of atoms was came upon by a greek philosopher Leucippus of Miletus and his student Democritus of Abdera. The theory is that the universe is made up of insole units called atoms.
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What did John Dalton add to the atomic theory?

Based on Dalton's story his theory is on experimental evidence. Dalton states that all atoms of a given element were exactly alike, and that atoms of different elements could join to form compounds.

Why was Dalton’s theory more successful than the previous theory?

Dalton's theory was more successful than the previous theory because he had evidence to support his theory.
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How did J.J. Thomson discover the electron?

JJ Thomson discovered the electron in 1897 by a series of experiments designed to study cathod rays, Which are mysterious rays in vacuum tubes. His cathode ray tube experiment showed that cathode rays were made up of charged particles that came from inside.

Describe Thomson’s model of the atom.

Thomson's model terrorized that an atom was a sphere positive energy i which electrons were randomly placed.
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What is Rutherford’s atomic model?

Rutherfods model described as a dense, tiny, and positively charged core called a nucleus, around which the light, negative constituents called electrons circulate at some distance.

How did he arrive at this model?

He tested Thomsons hypothesis by testing his "gold foil" experiment. Rutherford stated that if Thomsons model was correct then the mass was spread throughout the atom.

Sources

Holt Science Spectrum: Physical Science with earth and space science


http://dl.clackamas.edu/ch104-04/dalton's.htm