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Democritus
Democritus hypothesized that all matter is made up of atoms. He asked himself, "if you kept breaking an object in half, how many times will it break until it can no longer be broken?" He imagined the atom having no protons, neutrons, or electrons. -
Dalton
Dalton's atomic theory was that all elements are composed of atoms, atoms of the same element are the same, and atoms of different elements can be combined to make compounds. The method he used was performing a series of experiments on mixtures of gases. His atom was called the "Billiard Ball" model. -
Thomson
Thomson discovered the existence of electrons. He used a series of experiments designed to study the nature of electric discharge in a high-vaccum Cathode Ray as his method. The famous name for his model was the "Plum Pudding" model. -
Rutherford
Rutherford suggested the way the protons and electrons were eranged. The mass of the atom would spread throughout the atom. He used the "gold foil" experiment with a film of gold atoms. He thought the protons and the electrons are uniformly mixed throughout the atom. -
Bohr
He modified Rutheford's model by studying the electrons in orbits of fixed size and energy. Electrons travel in different orbits. He studied the atom with Rutheford and studied Park's theory about quanta. In his aromic model, there was no nucleus or neutrons, and the porton was in the center. -
Heisenberg and Schrodinger
They concluded that no expedient can measure the position or momentum of a quantum particle simultaneously. They did experiments to try to figure out the exact position of a particle. There is a cloud surrounding the nucleus containing the positions of the electrons. It was called the "Heisenberg uncertainty theory".
