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500 BCE
Plato
He found that there are only five solid shapes whose sides are made from regular polygons. -
500 BCE
The Alchemists
By laying doen the foundation of the Period Table of the elements. They broke down the chemical composition of fire, earth, wind, and water. -
400 BCE
Democritus
Invented the theory posited that matter is all made up of small indestructible units called atoms. -
1543
Nicolaus Copernicus
Solar System Model -
Robert Boyle
Discussed the possibilities of atoms existing. He proposed that elements are composed of "corpuscles" of various sizes and types that can be able to organize themselves into groups that represent different chemical substances. -
Antone Lavoisier
He determined that oxygen was a key substance in combustion. Also, total mass of products and reactants in a chemical reaction is always the same. -
John Dalton
Created the theory that all matter was composed of atoms. -
John Dalton
Billiard Ball Model -
Amedeo Avogadro
Created the hypothesis that equal volumes of different gases contain an equal number of molecules. -
JJ Thompson
Discovered electron, the first subatomic particle to be discovered. -
Dmitri Mendeleev
He is considered the most important contributor to the development of the periodic table. -
Pierre and Marie Curie
Discovered two new elements, radium and polonium. -
Sir Joseph John Thomas
Plum Pudding Model -
Albert Einstein
Proposed the quantum of light. He also started the equivalence of energy and mass through the theory of special relativity. -
Robert Millikan
Discovered the charge of an electron with his oil-drop experiment. -
Ernest Rutherford
He discovered that there are two types of radiation, alpha, and beta particles coming from uranium. He studies the radioactivity of the atom. -
Neils Bohr
Proposed an atomic structure theory that stated the outer orbit of an atom could hold more electrons than the inner orbit. -
Henry G. J. Mosely
He concluded that the atomic number is the number of positive charges in the atomic nucleus. -
Erwin Schrodinger
Used mathematical equations to describe the likelihood of finding an electron in a certain position. -
Erwin Schrodinger
Electron Cloud Model -
Werner Heisenberg
Formulated quantum mechanics in terms of matrices and discovered the uncertainty principal. -
James Chadwich
Discovered the existence of neutrons.