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460 BCE
Democritus is born
Democritus was born in Abdera. -
Period: 460 BCE to 370 BCE
Democritus Atomos
Democritus believed everything was made of of a very small particles called 'atomos'.And these atomos cannot be divided. He believed this because he thought if you get a stone and keep breaking it, at some point you cant break it any more.Fun Fact: Democritus believed atom vary in size and shape. -
400 BCE
Democritus Model of the Atom
[Democritus}(http://www.abcte.org/files/previews/chemistry/s1_p1.html) -
370 BCE
Democritus dies
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Period: to
John Dalton
John Dalton was born in Cumberland, England. Fun Fact: John Dalton knew all gases could be liquefied provided their temperature was sufficiently low and pressure sufficiently high. When coming to atoms he believed every thing are made of atoms, atoms can't be divided,and he contributed that all atoms combine in whole number to form compounds, atoms join together to make a new substance, and atoms have mass. Dalton -
Dalton's Atomic Theory
Dalton believed atoms have mass and atoms of join together to make a new substance he knew this because he put 12 grams of carbon and 16 grams of oxygen which reacted with each other to make 32 grams of carbon dioxide.The ratio of oxygen mass to carbon dioxide mass was 2 to 1. Which proved atoms made of different elements had different masses. In 1808, he expressed this feeling about atoms in his publishing of 'A New System of Chemical Philosophy'. -
J.J. Thomson is born
Born in Manchester, England. -
Ernest Rutherford is born
Born in New Zealand. -
Niels Bohr is born
Born in Denmark. -
Period: to
Erwin Schrodinger
Born in 1887 in Vienna, Australia. Dying in the year 1961. -
Thomson's Atomic Theory: Cathode Ray Experiment
Thomson conducted his cathode ray experiment.He noticed how far the rays traveled before they stopped.This told Thomson the particles in the rays were smaller than atoms were thought to be.
all Thomson sources -
Period: to
Werner Heisenberg: Cloud Model
Born in 1901 in Germany. Dying in 1976. -
Thomson's Plum Pudding Model; His beliefs are atoms are empty space, electrons are negatively charged and are in-beaded in a positively substance.
After the cathode ray experiment, he started doing experiments. Such as measuring the amount of heat the particles generated when they hit a target, deflecting cathode rays with magnetic fields, and more. He concluded from this experiment that Cathode ray particles were negatively charged,and 1000 times lighter than a hydrogen atom.After his findings, Thomson knew what his model, which was a positively charged atom with negatively charged atoms in them. And he called it the Plum Pudding Model. -
J.J. Thomson wins a Nobel Prize in Physics
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The Gold Foil Experiment: Rutherford's Experiment and His Mostly Empty Space
This experiment which was an experiment with a lead box,inside was a radioactive source and in front of that box there was a small opening,a piece of Gold foil was in front of it,and around all of that was a detector.According to Thomson's model all atoms of the source should go through the gold and to the other side.But every once in a while it would bounce to the side.Which disproves Thomson's model.And approves that there is a hard positively nucleus with electrons orbiting it. -
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Bohr's Atomic Model
Bohr discovered the atom a positively charge nucleus with negatively charged electrons orbiting it.He also believed that the electrons could jump different orbiting levels. In his model light is emitted when electrons from higher to lower orbit. Bohr used the atomic spectra to develop his model. Bohr's evidence for this model was quantum theory. So Bohr assumed electrons moved around the proton in a circle. -
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Erwin Schrodinger: Cloud Model
Erwin believed that an electron's path does not go in a exact path.Erwin's model was a nucleus{which had positively charged protons}surrounded by a electron cloud where the electron orbit. He believed where ever more dense the more likely the electron will be there. Erwin -
Werner Heisenberg: Gamma Rays
Werner believed you couldn't actually observe the electrons move in a circle. Werner wanted to focus on stuff you could observe. He use quantum physics and math to prove that electrons orbit a proton filled nucleus but those electrons didn't orbit in a circle. Werner conducted an experiment with gamma rays.He tried to observe the electron, but every time he tried to observe the electron with a high powered microscope it only got faster. He published this through Bohr editing it. -
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Erwin Schrodinger wins a Nobel Prize in Physics
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Ernest Rutherford dies
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J.J. Thomson dies
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