Atomic Theory Timeline by Delaney Mathes

1) Democritus: Theory of an Atom created in 400 B.C.

delaneym10 — 2024-03-07 14:21:05 UTC

He came up with the theory of the atom. Him and his students concluded that atoms could not be divided. They hypothesized that atoms were small, hard particles and that they all contained the same type of material. Though he was the first to suggest the theory of the atom, it wasn't a solid foothold in the fundamentals of chemistry till John Dalton proposed it.

2) John Dalton: Atomic Theory Model created in 1803-1808

delaneym10 — 2024-03-07 14:32:03 UTC

He experimented with gasses, which lead him to propose the modern atom theory. His model shows that an atom is a ball-like structure. This is because the concept of atoms having a nucleus and electrons was unknown at the time.

3) J.J. Thomson: Plum Pudding Model created in 1904

delaneym10 — 2024-03-07 14:41:26 UTC

This model is called the "Plum Pudding Model". His model showed that atoms have smaller electrons, negatively-charged electrons that were embedded in positively-charged "soup." He also stated that because the charges are of similar size, they cancel out each other's charge and neutralize the atom.

4) Ernest Rutherford: Rutherford Model created in 1911

delaneym10 — 2024-03-07 14:51:49 UTC

He studied the effects of bombarding thin gold foil with alpha particles. He observed how the alpha particles moved through the gold foil, this gave him the information needed to conclude what atoms looked like. He proposed that negatively-charged atoms surround the nucleus of an atom. He also claimed that electrons travel very fast in circular pathways.

5) Niels Bohr: Bohr Model created in 1913

delaneym10 — 2024-03-07 15:10:25 UTC

His model shows that electrons move in a fixed orbital pattern known as shells and not anywhere in between. He also explained that the shell has a fixed energy. Bohr modified Rutherford's explanation of the nucleus of an atom and turned it into electrons and their energy levels. His model also explains that electrons will have more energy if it's located away from the nucleus and less energy if located near the nucleus.

6) Aristotle, Schrodinger, Heisenberg, and Einstein: Other Theorized Models

delaneym10 — 2024-03-07 15:21:59 UTC

Aristotle: He did not believe in atomic theory. Believed that the elements of fire, water, air, and earth were the only substances. He believed that all substances were made from these core elements.

Schrodinger: The Schrodinger Model explains that electrons in an atom is a wave and tries to describe where electrons can be mostly found in regions of space or orbits.

Heisenberg: Proposed that electrons moved in a cloud-like formation. With the uncertainty principal, he concluded that he could only predict where an electron would be at a certain time. He also came up with the Matrix Formulation to do the predictions.

Einstein: In 1905, he mathematically proved the existence of atoms. This helped revolutionize the field of science through statistics and data analysis. Stated that any liquid is made up of molecules; futhermore, molecules are always in constant motion.