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400 BCE
Democritus
Democritus was a Greek philosopher who proposed the idea that matter could not be divided into smaller pieces forever. He claimed that matter was made of small particles called "atomos" -
Declaration of Independence signed
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John Dalton
John dalton said that all mater is made of atoms and atoms are indestructible. 2. All atoms of a given element have the same mass and properties. 3. Compounds are formed of two or more diffrent types of atoms. 4. A chemical reaction is a rearrangement of atoms. -
Civil war begins
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J.J Thomson
J.J Thomson discovered electrons and said they were negatively charged. He also doscovered that atoms can be broken. Into smaller pieces. -
1st World Series game
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Ernest Rutherford
Using his well known gold foil experiment ruthford overturned thomsons pudding model to show an atom had a heavy neucleas. He also showed that most of a atom is empty space. He also discovered Protons. -
Niels Bohr
Niels Bohr is credited for discorvering the neutron cloud. He said that when electrons are jumping from one orbit to another with low energy it produces a quantum is emitted -
WW1 begins
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James Chadwick
James Chadwick bombarded beryllium atoms with alpha particles and the result was what we now know as a neutron. -
WW2 begins
