1. The History of the Atomic Model In other words, the old guys who came up with the atom.

2. Democritus 460 BC - 370 BC A Greek philosopher proposed that all matter was composed of indivisible hard balls called atoms (Greek for uncuttable). A Greek philosopher proposed that all matter was composed of indivisible hard balls called atoms (Greek for uncuttable). Unfortunately he was unpopular and ignored. Unfortunately he was unpopular and ignored.

3. John Dalton 1803 Billiard Ball Model : viewed the atom as a small solid sphere. Billiard Ball Model : viewed the atom as a small solid sphere. But he got the ball rolling again to study the atom. But he got the ball rolling again to study the atom.

4. Joseph John Thomson 1897 Plumb Pudding Model: Proposed that the atom was a sphere of positive energy with negative particles imbedded throughout. Plumb Pudding Model: Proposed that the atom was a sphere of positive energy with negative particles imbedded throughout. He was awarded the Nobel Prize in physics in 1906 for discovering the electron. He was awarded the Nobel Prize in physics in 1906 for discovering the electron.

5. Ernest Rutherford 1910 Solar System Model: discovered that the atom is mostly empty space with a dense positively charged nucleus surrounded by negative electrons. Solar System Model: discovered that the atom is mostly empty space with a dense positively charged nucleus surrounded by negative electrons.

6. How Did He Know He beamed particles through gold foil and detected them as flashes of light. He beamed particles through gold foil and detected them as flashes of light. Most of the alpha particles went straight through the foil, but some were deflected by the foil and hit a spot on a screen placed off to one side. Most of the alpha particles went straight through the foil, but some were deflected by the foil and hit a spot on a screen placed off to one side.

7. Neils Bohr 1913 Neils Bohr 1913 Proposed that electrons traveled in circular orbits and that only certain orbits were allowed. Proposed that electrons traveled in circular orbits and that only certain orbits were allowed.

8. Erwin Schrodinger 1926 Electron Cloud Model: Using math Erwin found that an atom consists of a dense nucleus composed of protons and neutrons surrounded by electrons that exist in different clouds at the various energy levels. Electron Cloud Model: Using math Erwin found that an atom consists of a dense nucleus composed of protons and neutrons surrounded by electrons that exist in different clouds at the various energy levels.