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Democritas
- 440 B.C.
- Greek philospher
- Came up with concept of an anotm
- Said that atoms could not be divided and were moving
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Dalton
- Christian British chemisist and school teacher
- Developed the atomic theory
- Stated all things are made of atoms
- Same atoms from same thing
- Can join to make new substance
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Thomson
- 1817
- Discovered small particles inside the atoms
- Expiriemented with a Cathode-Ray Tube
- Positive could move a beam of particles
- Named negative particles corpuscles
- Now called electrons
- Plum pudding model showed the negative charges and all the extra space
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Rutherford
- Discovered the atom had a smal dense nucleus that had positive charges
- Did gold foil experiment that aimed charged particles at a thin sheet of gold
- Wanted to fined out where positive particles go
- + charges passed close to nucleus deflected away
- particle that hit nucleus would be deflected straight back
- atom mostly empty space
- Small dense + charged nucleus
- Travel around nucleus like planets
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Bohr
- 1913
- determined electrons travel around nucleus in definite paths
- Electrons could jump from one level to another too
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Heisenberg/ Schrodinger
- Said electrons dont travel in definite paths
- They cannot be predicted
- Current theory states electrons found in regions called electron clouds
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