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500 BCE
The Alchemists
The alchemists first introduced the idea of the four elements: earth, fire, water, and wind. The alchemists were a group of people that lasted until the late 1700's. -
437 BCE
Plato
Plato discovered there are only 5 solid shapes. He was convinced atoms came from these 5 shapes. -
400 BCE
Democritus
Democritus was a philosopher that first introduced the idea of an atom. -
Robert Boyle
Robert Boyle came up with the definition of an element: any substance that can't be broken down. He also helped prove the four elements wrong. -
Antone Lavoisier
Antone discovered that all matter is always conserved, even if they undergo chemical changes. -
The Billiard Ball Model
The Billiard Ball Model explains the atoms can lock together to make elements. People at the time did not know about atoms, so tight thought atoms were balls. -
John Dalton
John Dalton explained all matter is made of atoms. He also said the atom is the smallest building block. -
Amedeo Avogadro
Amedeo Avogadro said: two equal volumes have the same number of molecules. -
Dimitri Mendeelev
Dimitri Mendeelev invented the modern periodic table. This table ordered the elements based on weight. -
JJ Thompson
JJ Thompson discovered the Electron, the negatively charged part of an atom. He also made the plum pudding model. -
Robert Millikan
Robert Millikan discovered the positively charged part of the atom: protons. -
The Plum Pudding Model
The Plum Pudding model explains that the electron is negatively charged, it shows the negative electrons surrounded by positively charged matter. -
Albert Einstein
Albert Einstein proved the existence of atoms using math, completely revolutionizing science. -
Pierre and Marie Curie
Pierre. and Marie were a couple. that discovered that radiation is in a form of waves. Radiation waves are constant. -
Ernest Rutherford
Ernest Rutherford discovered that an atom is radioactive. -
The Solar System Model
The Solar system is a model based off of our solar system. It explains that the sun is the nucleus, and the electrons are the planets and parts moving around it. -
Neils Bohr
Neils Bohr discovered if an electron is taken away, it gives off radiation. He also discovered the atom ands won a Nobel Prize. -
Henry G.J. Mosely
Henry Mosely said the atomic number equals the number of protons in the atom. He also said there were more undiscovered elements. -
Erwin Shrodinger
Erwin Shrodinger was able to use the Bohr model to predict the likelihood of finding an electron at a certain position. -
The Electron Cloud Model
The electron cloud model explains that it is impossible to know exactly where an electron is at one moment. -
James Chadwick
James Chadwick discovered the neutron, the uncharged part of and atom. -
Werner Heisenberg
Werner Heisenberg discovered that a particles position can never be known exactly.