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440 BCE
Plato
Comes through a mathematical discovery by Empedocles, a fifth atomic type must exist which Aristotle later called "ether." -
400 BCE
Democritus
Believed that atoms were uniformed, solid, hard incompressible and indestructible. He also thought that they moved in infinite numbers through empty space until they stopped. -
330 BCE
Solar System Model
A model used to sort and order the planets.
( Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune ) -
Robert Boyle
Boyle says if the volume of a gas is decreased, the pressure increases proportionally. -
Antoine Lavoisier
Antoine Lavoisier found that the total mass of products and reactants in a chemical reaction are always the same. -
The Alchemists
They toiled countless hours over the furnace until they stumbled upon serval new substances. Also known as the elements of the periodic table. -
The Billiard Ball Model
John Dalton created The Billiard Ball Model because he thought atoms were the smallest particles of matter. -
John Dalton
His atomic theory proposed that all matter was composed of atoms and indestructible building blocks. -
Amedeo Avogadro
Avogadro thought that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. -
Dmitri Mendeleev
Dmitri found that all the known chemical elements were arranged in order if increasing atomic weight. He also is considered the "father" of the Periodic Table. -
Robert Millikan
Discovered that there is a fundamental electric charge. The charge of the electron. -
JJ Thompson
Experimented with cathode ray tubes. While doing so, he had shown that all atoms contain tiny negative charged, subatomic particles or electrons. -
Plum Pudding Model
J.J Thompson made a model that explains electrons. Electrons that are surrounded by a positive. -
Pierre and Marie Curie
French physicists Pierre and Marie Curie, discovered the strongly radioactive elements, Polonium and Radium. -
Albert Einstein
Albert Einstein mathematically proved the existence of atoms and helped revolutionize all of the scientists through the use if statistics and probability. -
Ernest Rutherford
Ernest Rutherford found that the atom is mostly filled with just empty space. -
Niels Bohr
Niels Bohr proposed a theory of the hydrogen atom. His model explained why the atoms only emit light of fixed wavelengths. -
Henry G.J. Moseley
Henry Moseley concluded that the atomic number is the number of positive charges in the atomic nucleus. -
Erwin Schrödinger
Erwin Schrödinger was an Austrian Physicist who took the Bohr model one step further. Schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position. -
Electron Cloud Model
Erwin Schrödinger made a model that shows a particular area in which an electron is likely to be. -
Werner Heisenberg
Werner Heisenberg contributed to the atomic theory through formulating quantum mechanics in terms of matrices and in discovering the uncertainty principle. -
James Chadwick
James Chadwick bombarded beryllium atoms with alpha particles. An unknown radiation was then produced.