-
450
Democritus (460-370 B.C.)
Democritus discovered that all things were made of atoms. He found this conclusion through observation, and explained this theory by arguing that without everything being made up of atoms, worlds could not be created. He claimed that atoms were tiny perticles that were indestructible, impercible, to the senses, and composed of exactly the same matter. -
450
Aristotle (300 B.C.)
Aristotle discovered that matter must be made of smaller pieces because things can continuously be broken into smaller pieces. Aristotle believed thath the elements were based off of things like water, fire, earth, etc. He used evidence from experiments by breaking objects into smaller sections. Aristotle belived that there were smaller things that existed, but did not know what they looked like. -
Dalton (1766-1844)
Dalton applied the concept of adding atomic weight to the current model of the periodic table in 1803. He believed that all matter is made up of atoms. He also stated that all atoms of a particular element are identical, and that compounds are formed by two or more different kinds of atoms. He found this through mathematics and his knowlege of physics. he belived the atom was a mass of positive forces with negatvie forces scattered throughout the atom. -
Thomson
Thomson discovered the elctron in 1897 ans investigated the charge and mass of the elctron. He also separated atoms by atomic weight. He proved that isotopes existed with the element Neon, and invented the "Plum Pudding" (not accepted model today) model of the atom. Thomson used the mathematical theory of elctricity and magnetism to discover the electron. Thomson believed that the atom looked like a mass of positive forces with negative charges dispersed throughout the area. -
Bohr (1885-1962)
He discovered that protons are in the nucleus of the atom and electrons surround it. He claimed that electrons only move in certain paths. He determined that outer electrons decide the element's chemical properties. He used theories and experiments from past scientists to come to these conclusions. Bohr thought the atom was a circle with a nucleus consisting of protons, with electrons on fixed, outer paths. -
Rutherford
Rutherford discovered that there was a positive charge existing in atoms, rather than just hypothesising that there was. He gathered evidence throughout experiments by shooting alpha particles at gold foil. The curved path of the particles was an indicator that a positive charge was present. He determined that the atom looked like a ball with a nucleus consisting of a postive charge with negative forces outside the nucleus. -
Heisenberg and Schrodinger
Both discovered that fast moving electrons cause a cloud of electrons outside the nucleus, rather than fixed paths. They used theories and observations from past scientists to claim these findings. Both thought that the atom consisted of a nucleus in the center of the atom with a cloud of electrons on the outsisde of the nucleus. Called the "Electron Cloud Model" and is accepted today. -
Bibliography
Coffeu, Jerry. Bohr's Atomic Model. N.d. Photograph. Www.universetoday.com, n.p.
"Dalton and the Atomic Model - Google Search." Dalton and the Atomic Model - Google Search. N.p., n.d. Web. 26 Feb. 2014.
"Democritus." Javascript:__doLinkPostBack('','mdb~~mih%7C%7Cjdb~~mihjnh%7C%7Css~~JN%20%22Columbia%20Electronic%20Encyclopedia%2C%206th%20Edition%22%7C%7Csl~~jh','');. 6th ed. N.p.: n.p., n.d. Print. -
Bibliograhy
"Erwin Schrodinger." Erwin Schrodinger. Purdue University, n.d. Web. 25 Feb. 2014.
Harvey, Nicole. "Unit 5 Concept 2." Unit 5 Concept 2 Notes. Zachary High School, Zachary. 25 Feb. 2014. Lecture.
Petterson, Kevin. "Unit 3 The Atom." Www.wikispaces.com. N.p., n.d. Web.
"Rutherford-Bohr Model." EPA. Environmental Protection Agency, n.d. Web. 26 Feb. 2014.
