Atomic theory Timeline

Aristotle 384 B.C -322 B.C.


THEORY: All matter was made of "The Four Elements". Fire, Earth,Air and Water.

Explanation: Didn't have any proof to prove his or support his theory

Model describes the Four Elements


Discovery: 460 B.C.

Name of model: The First Atomic Model

Experiment: Took a seashell broke it in half. Took that seashell and broke it in half and in half until he got fine powder. Tried to break that in half but couldn't. Discovered. The indivisible building block life an atom.

Description: model of the first atom

John Dalton 1766-1844

Discovery: 1803

Theory: Proposed that all matter is composed of atoms indivisible and indestructible building blocks

Explanation: All elements are composed of atoms (made up) of. It is impossible to divide or destroy an atom

Description: same as Democritus model

J.J. Thompson 1846-1940

Discovery: 1904

Model: Plum Pudding

Experiment: When experimenting with gas discharge tubes. Noticed movement in a tube called from the negative nod of the tube to the positive end. Rays were made up of negatively charged particles.

Description: Each atom was an sphere filled with negatively charged fluid

Ernest Rutherford 1871-1937

Discovery: 1911

Name of model: Plum pudding model

Experiment: The bold foil experiment. Taking a thin sheet of gold foil. Using special equipment to shoot alpha particles at the gold fail. Most passed back or were deflected as if they had hit something. Known as the Geiger–Marsden experiment.

Description: Shows an atom with electrons orbiting around a positively charged nucleus 

Niels Bohr 1885-1962


Model:Energy Level Model

Explanation: He gave the electrons energy levels and that the electrons to be outside and around the nucleus

Description: the electrons had levels that went around the nucleus

Louis de Brogile 1892-1987


Theory: Quantum theory

Explanation: Predicting the wave of nature of elections. That all matter have properties
Erwin Schrödinger 1887-1961


Model: Electron Cloud

Explanation: Discovered that electrons don't move in orbits (or in set paths at all). His Schrödinger Cat Paradox. To imagine a cat, poison, Geiger Counter, radioactive material and a hammer. If the the Geiger Counter detectived the radioactive material then the hammer whole smash the poison killing the cat but you wouldn't know the outcome without opening the box. So the cat would be in a Zombie state of dead or alive.

Description: His Equation to his Quantum Wave Theory

James Chadwick 1891-1974

Discovery: 1932

Model: Neutrons

Experiment: studying Beryllium radiation an Ionization counter and a cloud chamber. Found that the wax could be replaced with other light substances even Beryllium and that protons are still produce

Description: discovery on Neutrons

London, Love In. "The Atom Timeline." Timetoast. Schooltimetoast, 1 Jan. 2007. Web. 19 Feb. 2017. <>.

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