Timeline of Atom Models

By: Lainey Cristan

Ancient Greek Model

In 400 B.C Democritus found out that you can cut the object in half but eventually you will get to a small particle that can not be divided.

In 350 B.C Aristole discovered that the Earth comes in four elements: Earth, Air, Water, and Fire.

The Dalton Model

In 1803, John Dalton theorized that the atom was a tiny sphere. He stated that all atoms make up matter, atoms can not be divided, elements that were made up with the same kind of atom, and different elements were made up of different combinations of atoms. Dalton also said that in the chemical reaction none of the atoms disappear, they are rearranged.

Thompson Model

In 1897, Joseph Thompson proposed that atoms were tiny spheres of positive electricity with little pieces of negative electricity floating around in them. He called the negative pieces "electrons" and the model "The plum pudding model". He also said that there are smaller particles than the atom.
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Rutherford Greek Model

In 1908, he performed an experiment where he shot tiny particles out of a sheet of gold foil. Most of the particles passed through, telling him that an atom is mostly empty space.

Bohr Model

Bohr's model consist of a central nucleus surrounded by tiny particles called electrons that are orbiting the nucleus in a ring. These electrons are spinning so fast around the nucleus of the atom, that they would be a blur if we could see particles that small. The electrons actually chandelier their orbit with each revolution.
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Broglie and Schrodinger

They theorized that the Bohr model was incomplete and that electrons don't orbit like planets. Instead they proposed that the electrons existed in clouds around the outside of the dense nucleus. Their main idea is that electrons behave like particles and waves at the same time. It is impossible to predict exactly where they are , making them look like a cloud.
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