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350
Aristotle
Aristotle didnt believe the atomic theory. He believed that all things were made of Earth, Water, Fire, and Air. He used deductive and inductive reasosning for his thinking. He didnt have a model for the fact he didnt believe atoms exist . -
400
Democritus (BC)
Democritus came up with the idea that all matter contains atoms. He reasoned that atoms were the smallest part of matter, and could not be broken down further. The experiment he used was tearing a piece of paper until it couldnt be torn anymore . He believed an atom was shape like a marble. -
Dalton
Dalton's theory was based on the premise that the atoms of different elements could be distinguished by differences in their weights. He stated his theory in a lecture to the Royal Institution in 1803. The theory proposed a number of basic ideas: All matter is composed of atoms
Atoms cannot be made or destroyed
All atoms of the same element are identical
Different elements have different types of atoms
Chemical reactions occur when atoms are rearranged
Compounds are formed from atoms. -
Thomson
atomic theory was based on the fact that atoms are made up of small particles. He did experiments on light travelling through a tube with charge plates on its sides. He observed that the light bent towards the positive plate, thus made up of particles. His model was known as the Plum Pudding -
Rutherford
atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons. This model suggested that most of the mass of the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space. Rutherford came to this conclusion following the results of his famous gold foil experiment. This experiment involved the firing of radioactive particles through minutely thin metal foils. HIs Model was a neutron with electrons around it. -
Bohr
He proposed that electrons orbit the nucleus without losing energy. One observation was the experiment that showed an orbbit was big in size it had alot of energy. His model looked like the Solar System. -
Heinsberg and Schrodinger
the late 1920's both of these men had essentially the same theory. It proved that no experiment can measure the position and momentum of a quantum particle simultaneously. Scientists call this the "Heisenberg uncertainty principle." Meaning that when someone is trying to figure out the exact position of a particle, uncertainty in the momentum gets larger. Which finally concludes that there is simply just a cloud surrounding the nucleus containing the approximate positions of the electrons wit
