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400
Democritus' Atomic Theory (400 BC)
Democritus proposed the idea, through observation, that the atom was the smallest piece of matter and could not be divided. -
400
Aristotle's Atomic Theory (400 BC)
Suggested that all matter was made of smaller portions of fire, earth, water, and air. He discovered this through observation and philosophy. -
Dalton's Atomic Theory
Dalton proposed that all matter is made of indivisible and indestructable atoms, that differ from element to element. He discovered this through experimental obervations, Another name for his atomic model is "The Billiard Ball." -
Thomson's Atomic Theory
Thomson identified the negatively charged particle, known as the electron. He used a cathode ray tube to make his discoveries. Another name for his atomic model is the "Plum Pudding Model," -
Rutherford's Atomic Theory
Rutherford discovered the nuclear atom, using the gold-foil experiment. -
Bohr's Atomic Theory
Discovered that electrons orbit the nucleus without losing energy and could only move in fixed orbits of specific energies. -
Heisenberg and Schrodinger's Atomic Model
Discovered that electrons do not move in well-defined orbits. They made this discovery through an experiment where they shined a wavelength light on an electron. Schrodinger's model is also known as the "Electron Cloud Model,"
