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427 BCE
Plato
Introduced that geometric forms serve as atoms like how atoms mathematically break down to triangles and other element are other shapes
https://www.sutori.com/en/story/the-development-of-the-atomic-theory--QpgMYDuccQhEzL42Pt51mUPn -
400 BCE
Democritus
Was the first to suggest any type of atomic theory. He thought that every material had its own "type" of atoms and that no matter how small its cut up, it will always remain with the same properties
https://historyoftheatomictheory.weebly.com/democritus.html -
Robert Boyle
proposed that elements are made of "corpuscles" of various types and sizes that are able to organize themselves into groups that show different chemical substances. https://historyoftheatomictheory.weebly.com/robert-boyle.html -
Antone Lavoisier
He began the conversation about what an atom really is https://historyoftheatomictheory.weebly.com/antoine-lavoisier.html -
The Alchemists
-They played down the foundation of the modern day periodic table of elements https://prezi.com/t50cihtay12m/alchemy-and-its-contributions-to-the-atomic-theory/ -
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John Dalton
Daltons theory: Matter composed of atoms, atoms are invisible and indestructible, atoms of a given element are identical in size, mass, and chemical properties, atoms of specific elements are different than other elements, in chemical reactions atoms separate, combine, and rearrange. https://historyoftheatomictheory.weebly.com/john-dalton.html
Also created the Billiard ball model, he thoughts that atoms were the smallest, hard sphere particles alike to pool balls. -
Amedeo Avogadro
Was the first scientist to realize that elements could exist in molecules instead of just individual atoms.
https://www.famousscientists.org/amedeo-avogadro/ -
Dmitri Mendeleev
Created the periodic table or elements which were arranged in the order of their increasing atomic weight.
https://www.britannica.com/biography/Dmitri-Mendeleev -
Robert Millikan
Discovered the value for electron charge through the oil drop experiment. https://study.com/academy/lesson/robert-millikan-biography-atomic-theory-oil-drop-experiment.html -
JJ Thompson
Discovered electrons and proposed the Plum Pudding model which shows how negatively charged electrons are surrounded by positively charged volume https://www.sciencehistory.org/historical-profile/joseph-john-j-j-thomson
https://www.khanacademy.org/science/chemistry/electronic-structure-of-atoms/history-of-atomic-structure/a/discovery-of-the-electron-and-nucleus -
Pierre and Marie Curie
Discovered 2 radioactive elements. Polonium and radium.
https://www.britannica.com/science/atom/Discovery-of-radioactivity -
Albert Einstein
Mathematically proved the existence of the atom https://www.ans.org/news/article-969/albert-einstein-and-the-most-elemental-atomic-theory/#:~:text=Einstein%20also%20in%201905%20mathematically,use%20of%20statistics%20and%20probability.&text=Atomic%20theory%20says%20that%20any,always%20in%20random%2C%20ceaseless%20motion -
Ernest Ruthford
He found that there was something in the middle of an atom called a nucleus. This led to the solar system model, which describes the atom as a massive positive central entity (nucleus/sun) and orbiting it are negative entities (electrons/planets)
https://historyoftheatomictheory.weebly.com/ernest-rutherford.html
https://socratic.org/questions/what-is-the-problem-with-a-solar-system-model-of-the-atom -
Henry G. J. Mosely
Proved that every element has an identity that is determined by the amount of protons its made of.
https://www.famousscientists.org/henry-moseley/ -
Neils Bohr
He studied structure of the atom and suggested that electrons didn't spiral into the nucleus but but orbited in different levels and the more energy an atom gives off the closer it is to the nucleus, also, the more it absorbs the further away it is.
https://historyoftheatomictheory.weebly.com/niels-bohr.html -
Erwin Schrodinger
Used math to show the likelihood of finding an electron in a certain position which led to the electron cloud model which was basically just a model of the atom. http://www.abcte.org/files/previews/chemistry/s1_p6.html
https://www.nuclear-power.com/nuclear-power/reactor-physics/atomic-nuclear-physics/fundamental-particles/what-is-electron-properties-of-electron/electron-cloud/ -
Werner Heisenberg
Formulated quantum mechanics in terms of matrices and discovered the uncertainty principal which says that the position of a particle and its momentum cannot both be know
https://www.britannica.com/biography/Werner-Heisenberg -