The Atom Theory Timeline!

All the Important dates about the Atom Theory

The Ancient Greek Model

When in 400 B.C Democritus theorized that if you were to cut something into smaller and smaller pieces, you would eventually get to the uncuttable form of the element. He named them Atomos which was Greek for uncuttable.


His theory also influenced Archimedes when he expanded on the theory, claiming that there were 4 pure elements: Fire, Water, Air, and Earth.

The Dalton Model

In 1803, A man by the name of John Dalton theorized that all matter are made of small hemispheres. He then named the model, the Dalton model, after himself.

The Thompson Model

In 1897, Mr. Joseph Thompson thought that an atom is a miniscule sphere of positive energy with little pieces of negative energy inside. He named the little bits of negative energy "electrons". He named the model the Plum Pudding Model.

The Rutherford Greek Model

The year is 1908. Ernest Rutherford comes up with a new atom theory. He theorized that an atom had a relatively large nucleus filled with positive energy, and that the electrons flew around the nucleus, emitting a negative charge.

The Bohr Model

In 1913, Niels Bohr thought that the central nucleus was made of sub-atomic particles called protons and neutrons. Surrounding the nucleus is the electrons, spinning around the nucleus like planets.

And finally, the Broglie & Schrodingler model

In the 1920's, two men by the name of Broglie and Schrodingler theorized that electrons didn't orbit around the nucleus, but instead flew around the nucleus as a wave.