-
400
Aristotle
Thought all matter consisted of one of four elements; fire, water, earth and air and that each was defined by its dryness, hotness, coolness and moistness. -
Period: 400 to
Early Atomic Ideas
-
460
Democritus
Used no evidence to support idea but rather used common sense. -
Period: to
Early Atmoic model/history
-
John Dalton
Dalton sort of made an educated guess to what an atom was. Daltons atomic theory states: Elements are made of extremely small particles called atoms. Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties. Atoms cannot be subdivided, created, or destroyed. Atoms of different elements combine in simple whole number ration. in chemical reactions atoms are combined, seperated or rearranged -
William Conrad Roentgen
Discovered X-rays go through matter -
JJ Thompson
Thompson's model consisted of a positivly charged body and electrons floating around on the body. Also called Plum Pudding model -
Hantaro Nagaoka
Hypothesized that electrons orbited around a center point or nucleus. -
Rutherford Experiment
Using a atom thin gold foil, Rutherford launched particles to see to the foil. A majority of the atoms passed right through with some small degree of deflection while others reflected straight back -
Rutherford's model
Rutherford said that atoms moved around a central indestructible center or nucleus. Atomic model did not explain chemical reactions. -
Niels Bohr
Proposed that atoms orbit around the nucleus in fixed paths and they could gain energy and go to a higher orbit and then when they lose energy go back down. -
Louis de Brogile
Proposed that everything; both matter and energy traveled in waves. Explained why movement is the way it is on the atomic level. -
Erwin Scrhodinger
Using de Brogile's movement theory Schrodinger thought that the atoms would move in clouds rather than in defined orbits -
James Chadwick
Proved existance of neutrons.
