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427 BCE
Plato
Plato introduced the atomic theory to the Alchemists which he was a part of. He also started math and helped create most of the math systems used today. -
400 BCE
Democritus
Democritus believed that atoms were like rocks and flames. He was the first person to find atoms and came up with the terms atomos, but that was soon changed to atoms. He also helped create the periodic table of elements. -
700
The Alchemists
The Alchemists consisted of more than 10 ten people, but some people that were recognizable and important, are Plato, Democritus, and Leucippus. The Alchemists were known for creating most of the atomic theory. -
Robert Boyle
Robert Boyle published the Boyle's Law. Boyle's law states that at constant temperature the volume of a given mass of a dry gas is inversely proportional to its pressure. Boyle also published the Skeptical Chemist. -
Antoine Lavoisier
Antoine Lavoisier discovered that water is a compound of many different elements. He helped define the word element as something that cannot be broken down into simpler substances -
Billiard Ball Model
The Billiard Ball Model was used to show that atoms are the smallest particle of an element. Shows that atoms of different elements had different masses. Improved by JJ Thomson who discovered the electron in 1897. -
John Dalton
John Dalton helped finish the atomic theory. John Dalton helped determine an atom's mass of various elements. -
Amadeo Avogadro
Amadeo Avogadro proposed the molecular theory or otherwise known as Avogadro's theory. He was also the first scientist to realize that elements could exist in the form of molecules. -
Dmitri Mendeleev
Dmitri Mendeleev created and finished the Periodic Table of Elements which saw that certain elements dint just have one atom, some of them had many but were the same kind of atom. -
JJ Thomson
JJ Thomson discovered the first subatomic particle, the electron. He also found the first certain stable elements. -
Pierre and Marie Curie
Pierre and Marie Curie discovered strong radioactive elements and Marie Curie helped create the definition of radioactivity. -
Albert Einstein
Albert Einstein mathematically proved that atoms were real and how they functioned. Albert Einstein also did an experiment called the photoelectric effect. -
Ernest Rutherford
Ernest Rutherford established the Rutherford's atomic model. Found that the nucleus was being surrounded by electrons which helped contribute to science today. -
Plum Pudding Model
The Plum Pudding Model suggested that the atom was a sphere of positivity charged ball with negatively charged atoms scattered evenly throughout. Later replaced by the Rutherford Model. Made by JJ Thompson -
Henry G. J Mosely
Henry G.J Mosely found major properties of certain atomic particles. He also redefined the idea of atomic numbers in previous states. -
Niels Bohr
Niels Bohr was the first person to create the quantum concept. He also won the Nobel Peace Prize for Physics for studying the structure of atoms and other radiation levels. -
Solar System Model
The Solar System Model was used for describing atoms as consisting of small positively charged nucleuses surrounded by electrons that move in a circular orbit around the nucleus much like a planet orbiting its' sun which sprouted the idea of the Solar System Model. Made by Niels Bohr -
Robert Millikan
Robert Millikan made the Oil-Drop Experiment which helped him with an electro-charged experiment. He also won the Nobel Peace Prize for Physics -
Werner Heisenberg
Werner Heisenberg worked on the atomic theory. He also discovered the nucleus' connection to protons and electrons. -
Erwin Schrödinger
Schrödinger devised an equation for quantum mechanics. He also found that one atom = one electron. -
Electron Cloud Model
The Electron Cloud Model was used to map out atomic orbitals for electrons around a nucleus. This model was also used to assign electrons to different atomic orbitals and explain patterns in the Periodic Table of Elements. Made by Schrödinger -
James Chadwick
James Chadwick helped prove the existence of neutrons and what they do. He was awarded the Hughes medal in 1932.