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428 BCE
Plato
Plato came up with elements. He believed in the five different forms of elements; wood, fire, earth, metal, and water. -
400 BCE
Democritus
Democritus made a theory posited that matter is all made up of small indestructure units called atoms. -
760
The Alchemists
The Alchemists started the belief that all metals were formed from two principles: mercury and sulfur -
1543
Solar System Model
The Solar System Model is a model of atoms as the consisting of a nucleus with a number of electrons in orbit around that nucleus. -
Robert Boyle
Robert Boyle focused on the study of gases. He proposed that elements are composed of "corpuscles" of various sizes and can organize themselves in groups. -
Antone Lavoisier
Antone Lavoisier grouped elements as substances: gases, metals, non-metals, and physical and chemical substances. -
John Dalton
John Dalton proposed that compounds were atoms from different elements combined together and that are consisted of atoms that are identical and have the same mass. -
Billiard Ball Model
The Billiard Ball Model was the finding that an atom is to be a ball-like structure. It concepts of the atomic nucleus and electrons. -
Amadeo Avogadro
Amadeo Avogadro discovered equal volumes do gases at the same temperature and pressure contain the same number of molecules. -
Dmitri Mendeleev
Dmitri Mendeleev created the periodic table. He made the discovering of different elements easy to categorize. -
JJ Thompson
JJ Thompson determined the charge to mass ratio of electrons. -
Pierre and Marie Curie
Pierre and Marie Curie discovered polonium and radium, which helped us understand radioactivity. They discovered that polonium and radium gave off tiny atoms tat disintegrated inside elements. -
Plum Pudding Model
The Plum Pudding Model is an atom with a positive and negative charge. It's the finding that an atom is made like a sphere with a positive charge but has negatively charged electrons embedded in it. -
Albert Einstein
Albert Einstein proposed the quantum of light in which he states that light is like a particle and has a wave nature that is giving a dual nature. He also started the equivalence of energy and mass through the theory of special reactivity. -
Robert Millikan
Robert Millikan discovered the charge of an electron with his oil drop experiment. -
Ernest Rutherford
Ernest Rutherford discovered a small, dense, positively charged nucleus as the result of the alpha particles scattering gold foil experiment. -
Neils Bohr
Neils Bohr proposed an atomic structure theory, that stated that the outer orbit of an atom could more electrons than the inner orbit. -
Henry G. J. Mosely
Henry G. J. Mosely made the discovering of number of protons in an element and its atomic number. -
Werner Heisenberg
Werner Heisenberg discovered the uncertainty relation. He formulated a type of quantum mechanics based on matrices. -
Erwin Schrödinger
Erwin Schrödinger studied the behavior of electrons within atoms. Which could be explained by treating them mathematically as matter waves. -
Electron Cloud Model
The Electron Cloud Model is a model showing how electrons move in a cloud. It's the region of negative charges, which surrounds the nucleus. -
James Chadwich
James Chadwich discovered that there are neutrons in an atom which helped understand the building blocks of atoms.