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500 BCE
The Alchemists
Aristotle's idea was by treating different metals to change the structure of the item, the item could become more valuable. Even though he failed to turn items into gold, he ended up creating a scientific process which would help him discover the atom. -
460 BCE
Democritus
Democritus said that everything is made up into tiny bits, which are called atoms. He said that these atoms are indestructible and he said that different shapes of atoms gave them different properties. -
427 BCE
Plato
Plato introduced the theory that ideal geometric serve as atoms, the atoms are mathematically broken down into triangles -
Robert Boyle
He was known as "The Father of Chemistry" because of his discovery that atoms must exist based on the relationship of pressure and volume of gas. His theory called Boyle's Law says that because a fixed mass of gas can be compressed, gas must be made of particles or atoms because there is space between them. -
Antoine Lavoisier
Lavoisier was known for his skills when experimenting and enjoyed separating the oxygen molecule from HgO. He later created the Law of Conservation which states that matter can neither be created nor destroyed. -
John Dalton
Dalton's Atomic theory states that everything is composed of atoms, which are indivisible building blocks of matter that cannot be destroyed. All atoms of elements are identical. -
Billiard Ball Model
The Billiard Ball Model, also known as the Solid Sphere Model, was the first atomic model developed by John Dalton. The model shows that an atom is a solid sphere that cannot be broken up into smaller particles. -
Amadeo Avagadro
Avagadro was best known for his hypothesis that states that equal volumes of different gases contain an equal number of molecules. He was also the first scientist to discover that elements could exist in the form of molecules instead of individual forms. -
Dmitri Mendeleev
Mendeleev discovered that when all the known chemical elements are placed in order of increasing atomic weight, the results displayed a recurring pattern, or periodicity of properties within groups of elements. -
Plum Pudding Model
The Plum Pudding Model was a model representing the atom. This model was first proposed by JJ Thompson in 1904. The model explained the two properties of atoms that electrons are negatively charged particles and that atoms have no net electric charge. -
JJ Thompson
JJ Thompson discovered that the electron, the negatively charged particle in an atom. He also created the Thompson Atomic Theory, which had many scientist studying the electric discharge of a cathode ray tube. -
Pierre and Marie Curie
The Curie's discovered and isolated radium a new element which disintegrated into other elements. This proved that the atoms of one element at least were not indivisible. -
Albert Einstein
Einstein's biggest contribution was that he fully proved through usage of evidence that atoms exist. He was also able to show that electrons could leave metal through usage of light. He also created the mass energy equivalence equation. -
Ernest Rutherford
Rutherford's model described the atom as a tiny, dense positively charged core named the nucleus. The light, negative constituents called electrons circulate at some distance. -
Robert Millikan
Millikan viewed his cosmic ray photons as the "birth cries" of new atoms continually being created by god to interact entropy and prevent heat death. He was also Vice Chairman of the Nation Research Council during World War 1. -
Neils Bohr
Bohr proposed a model of the atom in which the electron was able to take only certain orbits around the nucleus. This model was the first to use the quantum theory. -
Henry G. J. Mosely
Mosely was an English physicist who experimentally demonstrated that the major properties of an element are determined by the atomic number -
Solar System Model
The Solar System Model demonstrates the relative positions and motions of the moons and planets in the Solar System. -
Werner Heisenberg
Heisenberg formulated quantum mechanics in terms of matrices and discovered that a particles position and momentum cannot both be known exactly. -
Electron Cloud Model
This model was made by Erwin Schrodinger and Werner Heisenberg. This model was made to visualize the most probable position of electrons in an atom. -
Erwin Schrodinger
Schrodinger's model says that the electron is aware and tries to describe the regions in a space or orbitals, where electrons are most likely to be found. -
James Chadwick
Chadwick was best known for his discovery of the neutron. A neutron is a particle that has no electric charge that, along with positively protons, makes up an atoms nucleus. this lead to Chadwick's discovery of the atomic bomb.