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450
Democritus(460BC)
Democritus said that matter is made up of small and hard particles in motion, with ideal qualities. He also said that these are surrounded by empty space, and have an infinite number of shapes. However, Democritus didn't have any real evidence."Atom History." Atom History. N.p., n.d. Web. 27 Feb. 2014. http://molaire1.perso.sfr.fr/e_histoire.html. -
450
Aristotle(460BC)
Aristotle dismissed the atomic idea as worthless, and people believed him. He provided the method of gathering scientific facts.He had his own method he created by gathering evidence.He didn’t have an idea of what the atom looked like.Walker, Jim. "History of Atoms." History of Atoms. N.p., Sept. 1988. Web. 26 Feb. 2014. -
Period: 450 to
450 BC-1930
This timeline is going to demonstrate how the different models of an atom were changed over time due to technology and new disccoveries. -
Dalton
Dalton believed that all matter is made up of indestructable atoms. He also believed that all atoms of a element are the same in mass. He also said that a chemical reaction is a rearrangment of atoms. His theory that was used was called Dalton's Atomic Theory. This information was collected from Mrs. Harvey's Unit 5,"A Brief History of Modern Atomic Theory." Chemistry Tutorial : History of Atomic Theory. N.p., n.d. Web. 25 Feb. 2014. <http://www.ausetute.com.au/atomichist. Concept 2 class notes. -
Thomson
Thomson discovered the electron. He knew that they were negative, and he thought all matter was positive. He made the atom model.He used a cathode ray tube.He thought it looked like “raisins stuck on the surface of a lump of pudding”.Walker, Jim. "History of Atoms." History of Atoms. N.p., Sept. 1988. Web. 26 Feb. 2014. -
Rutherford
Rutherford discovered that there was a large nucleus with an overall positive charge. He also said that 99% of the atoms mass is found in the nucleus. He discovered this during an expereiment called the Gold Foil Experiment."A Brief History of Modern Atomic Theory." Chemistry Tutorial : History of Atomic Theory. N.p., n.d. Web. 25 Feb. 2014. http://www.ausetute.com.au/atomichist.html. -
Bohr
Bohr stated that the electrons orbit the nucleus in orbits. He also presented the Bohr atomic model.He observed the atom, and made a theory, and for the first time, rules had to fit the observation, even if they conflicted with the theories for that time period.The famous name for his model was the Bohr Atomic Model, he thought it had rings.Walker, Jim. "History of Atoms." History of Atoms. N.p., Sept. 1988. Web. 26 Feb. 2014. "Chemistry Project : The History Of The Atom." Chemistry Project : -
Heisenberg
Heisenberg said, "to view an electron in it' s orbit, you must shine a wavelength of light in it that is smaller than the electrons wavelength." He said the small wavelength of light has a high energy, and the absorbed energy will change the electrons position. Heisenberg used the Quantum Thoery and the Uncertainty Principle to make his discovery. The uncertainty principle states that you can never find the precise location of an electron.N.p., n.d. Web. 27 Feb. 2014. <http://promokeur.ca/chemi -
Schrodinger
Schrodinger saw electrons as clouds, and introduced “wave mechanics”.He used wave mechanics as his method to make his discovery.He thought it looked like a cloud; it was the “Electron Cloud Model”."Chemistry Project : The History Of The Atom." Chemistry Project : The History Of The Atom. N.p., n.d. Web. 26 Feb. 2014. Walker, Jim. "History of Atoms." History of Atoms. N.p., Sept. 1988. Web. 26 Feb. 2014.
