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Plato theorized that the solid forms of matter are composed of indivisible elements shaped like triangles. -
Democritus theorized that atoms were specific to the material which they composed. -
Boyle discovered the volume of a gas is inversely proportional to its pressure. If the pressure goes up, then the volume goes down. -
The Alchemists believed that all metals were formed from two principles mercury and sulfur. -
Lavoisier defined the law of conservation of mass and discovered mass is neither created nor destroyed in chemical reactions -
Created in the early 1800's by John Dalton. Shows the shape of an atom. -
Dalton's theory suggested that all matter was comprised of indivisible and indestructible atoms with distinct masses and properties. -
Avogrado discovered that equal volumes of gas contain an equal number of molecules. -
Mendeleev invented the periodic table. -
Thompson discovered the electron. -
Pierre and Marie discovered radioactive elements such as polonium and radium. -
Created by Thomas Thompson in 1904. Shows the positive and negative charges in an atom. -
Einstein mathematically proved the existence of atoms. -
Millikan found the accurate determination of the charge carried by an electron. -
Rutherford established that the mass of the atom is concentrated in its nucleus. -
Mosely discovered the number of positive charges in the nucleus of an atom- the atomic number. -
Created by Neils Bohr in 1913. Shows the nucleus compromised of positive and neutral charges surrounded by negative charges. -
Bohr proposed a model of the atom in which the electron was able to occupy only certain orbits around the nucleus. -
Created in 1926 by Erin Schrödinger and Werner Heisenburg. Shows nucleus surrounded by a cloud of negative charges- the electrons. -
Chadwich discovered the neutron.