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500 BCE
The Alchemists
Were the first chemists. They contributed to the idea of the atomic theory. They also helped create the idea for the periodic table with their four earthly elements Liquids, Solids, Gases, and Fire
Britannica.com/science/chemistry/alchemy -
427 BCE
Plato
Inspired by a mathematical discovery Plato thought that the the base of all matter was five "solids" earth, water, fire, air and Plato's proposed element "ether" or the stuff of the stars.
http://abyss.uoregon.edu/~js/glossary/plato.html#:~:text=Plato's%20cosmology%20derives%20from%20a%20mathematical%20discover%20by%20Empedocles.&text=Plato%20was%20so%20imp
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https://www.britannica.com/biography/Plato -
400 BCE
Democritius
First theorized the existence of atoms and claimed all matter was made of tiny bodies he called the "atom" Greek for indivisible
Britannica.com/biography/Democritus -
Robert Boyle
He worked in the corpuscularian hypothesis which stated that everything was made of tiny but not divisible unit of universal matter in a clock work like universe(io nothin is random) in a piece called "The Sceptical Chymist" He also created with the help of Robert Hooke the air pump an used it to study pneumatics discovering the ideas of air pressure and vacuum.
Britannica.com/biography/Robert-Boyle -
Antoine Lavoisier
Created the Conservation of Mass Law. As well as believing that oxygen was vital for the process of combustion and named the element oxygen.
https://www.britannica.com/biography/Antoine-Lavoisier -
The Billiard Ball Model
Made by John Dalton (in the early 1800s?) who though of atoms as the smallest form of matter(partly true) he saw them as solid balls like in the pool-like game billiards. the small holes were used for hooks to hook them together representing a compound.
https://flexbooks.ck12.org/cbook/ck-12-middle-school-physical-science-flexbook-2.0/section/3.12/primary/lesson/daltons-atomic-theory-ms-ps/ -
John Dalton
Created and helped solidified the atomic theory with five rules.
1.Everything is made of atoms
2. Atoms are indestructible (proven false)
3. All atoms of one element share identical properties
4. And vise versa rule three
5. All compounds are made up of a whole number ration of atoms
Britannica.com/Biography/John-Dalton -
Amedeo Avogadro
Created his molecular hypothesis which stated that all gases of equal volume if at the same pressure and temperature have the same amount of molecules which helped with future calculations of elemental gases based off a chosen standard -
Dimitri Mendeleev
He created a periodical way to classify elements based off of atomic weight, leaving spaces where he thought future discoveries of new elements would be placed. io. he made the Periodic Table of Elements!
https://www.britannica.com/biography/Dmitri-Mendeleev -
J.J. Thompson
Found that all matter has particles that are much smaller than the atom's body he called corpuscles, now known as electrons.
https://www.britannica.com/biography/J-J-Thomson -
Pierre and Marie Curie
Discovered radio activity while conducting experiments on radium and polonium. Radioactivity meaning- the emission of ionizing, penetrating rays by some atoms. -
The Plum Pudding Model
Created by William Thompson( Lord Kelvin) and supported by J.J. Thompson. Stated that the negatively charged particles sat and remained inside of a positively charged particle.
https://www.britannica.com/science/Thomson-atomic-model -
Albert Einstien
He gave proof for the existence of atoms through experimenting and examining fluids (in this case still water) through a powerful microscope called the Brownian motion he was able to see the size of the atoms in the water.
https://www.britannica.com/biography/Albert-Einstein -
Robert Millikan
Discovered and determined the charge of electrons, and made break throughs in the photoelectric effect which is a process in where electrically charged particles shoot of or from a material that has absorbed electromagnetic radiation from 1909-1910
britannica.com/science/photoelectric-effect
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britannica.com/biography/Robert-Millikan -
The Gold Foil Experiment
Ernest Rutherford does his gold foil experiment
https://www.britannica.com/biography/Ernest-Rutherford/McGill-University -
Ernest Rutherford
Discovered that the atom was mostly empty space through his gold foil experiment from 1909-1911
https://www.britannica.com/biography/Ernest-Rutherford/McGill-University -
Nieils Bohr
He was the first to use the quantum concept which limits the energy in "certain discrete values" relating to molecules and the atom. As well as proposing a theory for the build of the hydrogen atom.britannica.com/biography/Niels-Bohr -
Henry G.J. Moseley
Using X-rays found that the most important properties of an element are determined by the atomic number not its atomic weight, while also crating the relation ship of the atomic number and the atom's nucleus' charge.
https://www.britannica.com/biography/Henry-Moseley -
The Solar System Model
Created by Neils Bohr this model probably the mot accurate today shows a central nucleus with electrons orbiting it in fixed orbits.
https://www.britannica.com/science/Bohr-model
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https://www.pas.rochester.edu/~blackman/ast104/bohr.html -
The Electron Cloud Model
Made by Erwin Schrodinger to show any possible varying orbit of an electron around it's nucleus. Was Also worked on by Werner Heisenberg and Neils Bohr.
https://www.msnucleus.org/membership/html/jh/physical/atomictheory/lesson1/atomic1g.html
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https://flexbooks.ck12.org/cbook/ck-12-middle-school-physical-science-flexbook-2.0/section/3.17/primary/lesson/electron-cloud-atomic-model-ms-ps/ -
Werner Heisenberg
He discovered a way to form quantum mechanics into matrices( a form of numbers in columns and rows in a rectangular shape) in 1925. As well as making his uncertainty principle relating to atomic nucleuses and electrons in 1927. His principle states that it is impossible to accurately measure both and objects position and velocity at the exact same moment and the more accurate you get one the less for the other.
https://www.britannica.com/biography/Werner-Heisenberg -
James Chadwich
After protons were discovered physicists wondered how some elements had greater atomic mass than their atomic number. James proved/ discovered the neutron the neutrally charged and third particles of elements. -
Erwin Schrodinger
Created thought experiment "Schrodinger's Cat" to represent atomic decay. The experiment is like this: A cat is locked in a box with an amount radioactive substance so that 1hr later there is an equal probability that an atom is either decaying or not. If the atom decays poison kills the cat. Until the box opens and the atom's wave function collapses then it is both decaying and not, so the cat is alive and dead at the same time.
https://www.britannica.com/biography/Erwin-Schrodinger
