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500 BCE
The Alchemists
The Alchemists were a group of people discovered that all metal contained mercury and sulfur. They also discovered that metal can turn into gold. -
460 BCE
Democritus
Democritus discovered that atoms make up all material things. -
428 BCE
Plato
Plato discovered that the ideal geometric forms serve as atoms. -
Robert Boyle
Robert Boyle discovered that substances cannot be broken down without breaking something else. -
Antone Lavoiser
Antone Lavoiser discovered that oxygen was the key substance in combustion. -
Billiard Ball Model
John Dalton created this model by using billiard balls as atoms. He wanted to show that the atoms were small. -
John Dalton
John Dalton discovered that all matter has atoms. -
Amedeo Avogadro
Amadeo Avogadro discovered that atoms could exist in the form of molecules. -
Dmitri Mendeleev
Dmitri Mendeleev discovered the periodic classification of elements. -
Neils Bohr
Neils Bohr discovered the theory of atomic structure:which states that all atoms look different. -
Pierre and Marie Curie
Pierre proved the existence of positively, neutral, and negatively charged ions. Marie discovered the radioactive elements polonium and radium. -
JJ Thompson
JJ Thompson discovered the electron. -
Plum Pudding Model
The Plum Pudding Model was discovered by JJ Thompson and showed electrons surrounded by a volume of positive charge. -
Albert Einstein
Albert Einstein proved the existence of atoms. -
Robert Millikan
Robert Millikan discovered the value of electron charge. -
Solar System Model
The Solar System Model was discovered by Neils Bohr and showed electrons orbiting the nucleus. -
Henry G.J. Mosely
Henry Mosely discovered the basis of the periodic table. -
Ernest Rutherford
Ernest Rutherford discovered that atoms consist of mostly empty space. He discovered that the mass is mostly in the nucleus. -
Erwin Schrodinger
Erwin Schrodinger calculated energy levels of electrons. -
Electron Cloud Model
The Electron Cloud Model was discovered by Erwin Shrodinger and shows electrons surrounding the nucleus. It also shows that it is hard to find the exact location of the electron. -
Werner Heinsberg
Werner Heinsberg discovered the theory that states that the exact position of a particle cannot be found. -
James Chadwich
James Chadwich discovered the neutron.