-
400 BCE
Democritus
Democritus was one of the first to suggest that all matter was composed of tiny discrete particles that would become known as "atoms".
https://en.wikipedia.org/wiki/Democritus -
400 BCE
Plato
Plato also was one of the first people to suggest the universe was made of tiny particles, shaped like triangles.
https://en.wikipedia.org/wiki/Plato -
1300
The Alchemists
They believed all metals were made of 2 elements, mercury and sulfur. They discovered many elements including phosphorus and antimony but falsely believed they were combinations of mercury and phosphorus.
https://uwaterloo.ca/chem13-news-magazine/february-2019/feature/ancients-and-alchemists -
Robert Boyle
Boyle developed the scientific method and developed the law between a gases' volume and its pressure which showed that they were made of tiny particles, the atoms.
https://en.wikipedia.org/wiki/Robert_Boyle -
Antoine Lavoisier
Antoine discovered Oxygen and Silicon. He also discovered the law of mass conservation, which meant that atoms could not be created or destroyed completely.
https://en.wikipedia.org/wiki/Antoine_Lavoisier -
Billiard Ball Model
The Billiard ball model was created by John Dalton in 1803. The model only consisted of the solid indivisible atom with no components, as the electron, neutron, and proton had not been discovered yet.
https://www.scienceabc.com/pure-sciences/dalton-atomic-model.html -
Amedeo Avogadro
Avogadro created Avogadro's law and number. The law states that any gas that have the same temp, volume, and pressure have an identical amount of molecules. The number is the ratio of the atomic mass to mass in grams, it is roughly 6.022*10^23.
https://en.wikipedia.org/wiki/Amedeo_Avogadro -
John Dalton
Developed theory of atomism and atomic mass.
https://www.britannica.com/biography/John-Dalton -
Dimitri Mendeleev
Formed the periodic law and table; made a way to organize elements
https://en.wikipedia.org/wiki/Dimitri_Mendeleev -
JJ Thompson
JJ Thompson discovered the electron, the fundamental component of an atom and it's bonds
https://en.wikipedia.org/wiki/JJ_Thompson -
plum pudding atomic model
The plum pudding model was created by JJ Thomson in 1904. It portrays negatively charged particles floating without orbits in a positively charged soup of matter.
https://en.wikipedia.org/wiki/Plum_pudding_model -
Robert Millikan
Robert Millikan discovered the negative charge of an electron and the photoelectric effect, which is the ejection of electrons from an atom using a gamma ray.
https://en.wikipedia.org/wiki/Robert_Andrews_Millikan -
Ernest Rutherford
Rutherford discovered the nuclear structure of an atom, and also discovered alpha and beta rays. -
Pierre and Marie Curie
The Curies discovered the property of radioactivity along with elements polonium and radium. https://en.wikipedia.org/wiki/Marie_Curie -
Henry GJ Mosely
Henry developed Mosley's lay which is the relationship between wavelengths of X-rays from metals and their atomic number
https://en.wikipedia.org/wiki/Henry_GJ_Mosely -
Solar System Model
solar system model was created by Niels Bohr in 1913. It describes atoms as consisting of a positively charged nucleus surrounded by a number of electrons in orbits around that nucleus, similar to a solar system.
https://www.britannica.com/science/Bohr-model -
Albert Einstein
Albert Einstein made many advancements to the atomic theory including the mass-energy equivalence (E=M(C^2)) and theories of
https://en.wikipedia.org/wiki/Albert_Einstein -
Neils Bohr
Proposed the model of that atom in which electrons orbit around the nucleus, which is used to this day.
https://en.wikipedia.org/wiki/Niels_Bohr -
Creation of the Electron Cloud model
The electron cloud model was created by Erwin Schrödinger and Werner Heisenberg in 1926. It is used to visualize likely positions of electrons in an atom instead of actual orbits of electrons.
https://www.vedantu.com/question-answer/does-the-electron-cloud-model-describe-class-11-chemistry-cbse-60af1b83f4d76d18e8666f1c -
Werner Heisenberg
Heisenberg was the main pioneer of the theory of quantum mechanics, the theory of how subatomic particles behave, and discovered allotropic (alternate) forms of hydrogen.
https://en.wikipedia.org/wiki/Werner_Heisenberg -
James Chadwick
Chadwick discovered the neutron, a fundamental component of the nucleus of an atom.
https://en.wikipedia.org/wiki/James_Chadwick -
Erwin Schrödinger
Schrödinger was also a pioneer of quantum mechanics, famous for the thought experiment that a cat (particle) left in a box with a 50/50 chance that it would die (decay) would be in a superimposed state of being alive or dead until it would be observed, then it would "choose" a state
https://en.wikipedia.org/wiki/Erwin_Schrödinger