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100
Democritus
Democritus believed that you could divide matter until you reach the smallest particle, the atom derived from the Greek word atomos which means indivisble -
320
Aristostle
Aristotle believed that matter could be divided infinitly and these beliefs were accepted for about the next 1500 years -
Antoine Lavoisier
Antoine Lavoiser was a French nobleman.Lavoiser discovered how oxygen applied in respiration and in combustion.He named multiple elements and discovered that water was a mixture of Hydrogen and Oxygen.Most importantly Lavoiser discovered law of conservation of mass which stated that mass can not be created or destroyed but it could be rearranged or changed in its form -
John Dalton
John Dalton was a British Chemist and helped to develop the modern atomic theory and modern chemistry.Dalton had an atom theory that connected different aspects of atom theory to form a theory that proved Aristotle's theory incorrect -
Spherical Model
Dalton created a model which was just an indivisible sphere -
Eugen Goldstein
Eugen Goldstein was a German physicist who worked with electrical tubes and discovered canal rays or anode rays which were just positively charged rays.His work with canal rays helped him to discover protons which were a positively charged subatomic particle which begin even more changes to the atomic theory and model -
J.J. Thomson
J.J. Thomson proved that atoms are made of smaller subatomic particles that have charges.By working with cathode ray tubes he ran electricity through it and the particles went towards the positive pole of a magnet because negatives are attracted to positives cathode rays must be negative and these were named electrons -
Plum Pudding Model
Thomson's Plum Pudding model consisted of a positively charged atom (pudding) with electrons scattered within it (plums) -
Ernest Rutherford
Ernest Rutherford perfromed the gold foil experiment which would lead to the discovery of the nucleus and proved that J.J. Thomson's Plum pudding model was not an accurate depiction of the atom -
Gold Foil Experiment
Ernest Rutherford used an alpha ray gun to fire alpha rays at a very thin piece of gold foil almost every particle went though but once in a while they would change direction this indicated that they were hitting something small and positively charged this would end up being the nucleus and would be the inspiration for the nuclear model -
Nuclear model
Rutherford's nuclear model was different than all its predecessors because this was the first model with a nucleus -
Robert Millikan
Robert Millikan was an American physicist who discovered the charge of an electron.He did this so that someone else could discover the mass of an elctron easily.In order for Millikan to find an electrons charge he used the oil drop experiment -
Niels Bohr
Niels Bohr was a Danish Physicist who was key to understanding the atomic structure as well as quantum theory and the field of quantum mechanics -
Bohr Model
Bohr's model replaced the Nuclear model because the nuclear model would not be able to support itself but the two are very similiar -
Erwin Schrodinger
Erwin Schrodinger was an Austrian Physicist who created the wave equation and was a leader in the field of quantum theory.Also Schrodinger created the model that would succeed Bohr's model -
Quantum Mechanical model
The Quantum Mechanical model kept the design of the Bohr model but supported Quantum jump and the Wave equation -
Werner Heisenberg
One of the main creators of Quantum mechanics and the first person to brin about the notion of the uncertainty principle .the rule that energy and time or position and momentum in quantum mechanics, cannot both be accurately measured simultaneously. -
James Chadwick
James Chadwick was a British physicist who discovered the neutron and determined that neutrons were a nuclear particle and not a combination of protons and electrons
