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Period: 350 to
Atomic Theory Timeline
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400
Democritus
Stated That..:
- Matter is made of particles called atomos.
- Atomos are solid and indivisible.
- Different kinds of atomos have different sizes and shapes. -
John Dalton
Stated That...:
- Matter is made of small particles called atoms.
-Atoms of a given element are identical, but they differ from those of any other element.
-Atoms are neither created nor destroyed by a chemical reaction, but they may be rearranged. -
J.J. Thompson
Stated That...:
-Discovered electrons with his cathode ray experiment.
-Developed “Plum Pudding” atomic model
*Negatively charges electrons in a “soup” of positive electrons -
Ernest Rutherford
Stated That...:
-Most of an atom’s mass is in its nucleus.
-The nucleus has a positive charge.
-Electrons are in fixed orbitals surrounding the nucleus. -
Niels Bohr
Stated That...:
-“Planetary” atomic model in which the nucleus is surrounded by electrons in orbitals with different energy levels.
n represents different energy levels -
Schrodinger
Stated That...:
-Quantum Mechanical Atomic Model
*Electron Orbitals have different shapes
-Electrons are both particles and waves of energy at the same time
