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450
Democritus
450B.C.
Democritus discovered the notion of an atom.
-A peice of matter is the smallest part - "Atom" -
450
Aristotle
In Ancient Greece, 450
All substances are made up of 4 elements - Earth, Wind, Fire, and Water -
John Dalton
"Father of Atomic Theory"
1. Atoms make up elements.
2. Atoms of the same element are identical.
3. Atoms of different elements are different.
4. Atoms of different elements react to form compounds.
5. Atoms cannot be created or destoyed - only changed.
Atom is just a soild sphere, -
J.J. Thomson
Found negative particle - electron.
Responsible for Cathod Ray Tube Experiment and Plum Pudding Model - which helped discover electron -
Marie and Pierre Curie
Reseached the feild of radiology.
A husband and wife team who were known reseach of radiology - which led to their discovery of the elements radium and polonium. -
Henri Becquerel
Dscovered radioactivity through his investigations of uranium and other substances. Shared his noble prize with the Curies in 1903. -
Robert Millikan
Masured the charge of an electron.
Oil Drop Experiment - dropped a drop of oil onto a hot plate and measured how strong the charge had to be to stop the oil from dripping. This discovered the electron. -
Ernest Rutherford
Discovered the nucleus.
Nucleus- Very small, very dense, postitive center.
Responsible for Gold Foil Experiment - found out that the atom wasnt just empty space and disproved the plum pudding model. -
Niels Bohr
He was the first to apply Quantium concept.
Niels Bohr is best known for the investigations of atomic structure and also for work on radiation.
He applyed quantium theory to Rutherfords experiments. -
James Chadwick
Found the Neutron
Worked under Rutherford.
he realized that there was something else that was adding to the mass, which is known as the nuetron. -
Quantium Model
Two models are used to today Bohrs and quantum mechanical model based on math.
The Quantum model is the most recent model of the atom.
