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450
Democritus (460)
Discovered nothing exists but atoms and empty space and that matter consists of invisible particles. He developed a theory that atoms can't be destroyed and atoms are always in motion, but he never knew the cause of the motion.He thought atoms looked like the material the object was made of. For example, water's atoms would be considered slippery and smooth.
Citation: Democritus: "Democritus Atomic Theory." Docstoc – Documents, Templates, Forms, Ebooks, Papers & Presentations. Docstoc, 27 Feb. -
450
Aristotle (384)
He developed the theory that atoms must be made of smaller pieces. He developed this theory because everytime you split an object in half, you would still have a smaller piece of that object. Citation: "HISTORICAL OUTLINE of the Atomic Theory and the Structure of the Atom." HISTORICAL OUTLINE of the Atomic Theory and the Structure of the Atom. N.p., n.d. Web. 25 Feb. 2014. -
Period: 450 to
HIstory of Atoms
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John Dalton
HIs theory was that all matter is made of atoms, but he didn't think that atoms could be separated or destroyed. He also developed the theory that a chemical reaction is a rearrangment of atoms and that atoms of the same element are identical. He distingushed atoms by the differences of their mass
Citation: "Dalton Atomic Theory." Dalton Atomic Theory. N.p., n.d. Web. 25 Feb. 2014 -
J.J Thomson
He discovered electrons and thought the atom looked like a sphere of positive matter that contained electrons. It was named the "Plum Pudding" model. His model explain the electrical properties of an atom due to electrons. Citation: Joseph John Thomson." Homepage of the Chemical Heritage Foundation. Chemical Heritage Foundation, n.d. Web. 25 Feb. 2014
"Development of the Atomic Theory." Development of the Atomic Theory. N.p., n.d. Web. 27 Feb. 2014. -
Ernest Rutherford
Rutherford was a student of J.J Thomson and proved his model incorrect. Rutherford and other scientists performed an experiment which they shot alpha paricles at gold foil and the waay the foil reacted proved that postitvely charged paricles were in the nucleus. This experiment is known as the "Gold Foil Experiment".
Citation: "Development of the Atomic Theory." Development of the Atomic Theory. N.p., n.d. Web. 27 Feb. 2014. -
Niels Bohr
Bohr's theory is similar to Rutherford's but the quantum theory is used. The quantum theory states that matter and energy do not cbey Newton's laws or other laws of classical physics. He belied that electrons orbited around the nucleus
Citation: "Neils Bohr - Atomic Model." Neils Bohr - Atomic Model. N.p., n.d. Web. 25 Feb. 2014.
"Bohr Model of the Atom." Bohr Model of the Atom. N.p., n.d. Web. 26 Feb. 2014. -
Werner Heisenburg and Erwin Schrodinger
They developed the uncertainty theory which states that he position and momentum can not be measured exactly.
Citation: Beyler, Richard. "Werner Heisenberg (German Physicist and Philosopher)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 25 Feb. 2014
