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Democritus
Date of Discovery: Unknown/Debated
Democritus developed the thought of the atom, He concluded that there is space between atoms, and that they are indestructible, will continue to be in motion, and there will be an infinite amount of atoms. -
Antoine Lavoisier
Date of Discovery: 1772
Lavoisier formulated a theory of the chemical reactivity of oxygen. -
Joseph Louis Proust
Date of Discovery: 1794
Proust published the Law od Definite Proportions that states that a compound is composed of exact proportions of elements by mass regardless of how the compound was created. -
John Dalton
Date of Discovery: 1803
Dalton took Democritus' atomic theory and modernized it and it consists of four main points that are more involved in explanation. -
Michael Faraday
Date of Discovery: 1830's
Faraday discovered that atoms had an electrical componenet, electrodes, and concluded that the electrical forces were responsible for the joining of atoms in compounds. -
Dalton's Indivisible Sphere Model
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Henri Becquerel
Date of Discovery: 1896
Becquerel decided to investigate whether there was any connection between X-rays and naturally occurring phosphorescence. He concluded this and named this process radioactivity. -
J.J. Thomson
Date of Discovery: 1897
Thomson is notabally recognized for the discovery of the electron and more importantally known for suggesting the model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces. -
Max Planck
Date of Discovery: 1900
Planck was the first to propose the quantum theory of energy. -
Robert Millikan
Date of Discovery: 1909
Millikan discovered the unit of charge for the electron which was then used to determine the calculation of mass of an electron and positively charged atoms -
Ernest Rutherford
Date of Discovery: 1911
Rutherford discovered the nuclear structure of the atom and also found that there is a dense, positively charged central region in the atomic mass. -
Lise Meitner
Date of Discovery: 1939
Meitner discovered the nuclear fission process while working with Otto Hahn and Fritz Strassmann and performed further tests on a uranium product they thought was radium but discovered it was barium. -
Otto Hahn
Date of Discovery: 1938
Hahn, also known as "The Father of Nuclear Chemistry", discovered that the element barium was produced when uranium atoms were bombarded with neutron while working with Fritz Strassmann, a fellow chemist. -
Albert Einstein
Date of Discovery: 1905
Einstein contributed countless ideas to the atomic theory and science in general. Some of his more notable works are Einstein's theory of relativity stating that energy equals mass times the velocity of light squared or E=mc^2. -
Niels Bohr
Date of Discovery: 1922
Bohr contributed the atomic model and created the atom as a small, positively charged nucleus surrounded by orbiting electrons. -
Erwin Schrodinger
Date of Discovery: 1926
He is a founder of quantum mechanics and created the Schrödinger equation. He also contributed to the wave theory of matter. -
James Chadwick
Date of Discovery: 1932
Chadwick discovered the neutron. -
Louis deBroglie
Date of Discovery: 1924
He developed the wave mechanics theory, which helped to explain the atomic scale. -
Thomson's Plum Pudding Model
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Marie and Pierre Curie
Date of Discovery: 1903
The husband and wife team expermiented with their own uranium-containing ore, and created the term "radioactivity" to describe the spontaneuous emissions that they studied. -
Glenn T. Seaborg
Date of Discovery: 1940
Seaborg was involved in the discoervery of nine transuranium elements which includes plutonium. -
Bohr's Planetary Model
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Schrodinger's Electron Cloud Model
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Quantum Mechincal Model
The combined genius of Heisenberg and Schrodinger. -
Aristotle
Date of Discovery: Unknown
Aristotle believed that knowledge could be obtained through investigating a physical object and also the four elements (air, earth, water and fire). He also said that no matter how many times you divide an object, you will always have a smaller piece of that object.
