History of the Atom Timeline by Grace Ringe and Ellen Manuel

By graceannringe
  • 450

    Aristotle (350 B.C.)

    He completely ignored Democritus. He believed in the four elements: fire, water, air, and earth. He said matter must be made of smaller pieces because things can continously be broken into smaller pieces. He used scientific facts for his discovery! He did not believe there was even an atom.
    "History of Atoms." History of Atoms. N.p., n.d. Web. 26 Feb. 2014.
  • 450

    Democritus (460B.C.)

    Democritus (460B.C.)
    He developed the idea of the atoms and that all matter contains atoms. He said atoms were smallest part of matter and could not be broken down anymore. He had no evidence for his theory he simply asked, "If you break piece of matter in half, and then break it in half, how many breaks will you have to make before you can not break it any further?"
    "MISTER RAKIB BLOG Pekanbaru, Riau, Indonesia." : SERATUS ENAM PULUH LIMA TAHUN SAT
    "History of Atoms." History of Atoms. N.p., n.d. Web. 26 Feb. 2014.

  • Dalton- "History of Atoms." History of Atoms. N.p., n.d. Web. 26 Feb. 2014. -and- "TimeRime.com - Developement of the Atomic Model Timeline." TimeRime.com - Developement of the Atomic Model Timeline. N.p., n.d. Web. 27 Feb. 2014.

    Dalton- "History of Atoms." History of Atoms. N.p., n.d. Web. 26 Feb. 2014. -and- "TimeRime.com - Developement of the Atomic Model Timeline." TimeRime.com - Developement of the Atomic Model Timeline. N.p., n.d. Web. 27 Feb. 2014.
    He tried to calculate the atomic weight of compounds and believed in the atomic therory. All matter is made of atoms, atoms are indivisible and indestructible. All atoms of a given element are identical in mass and properties. Compounds formed by combination of two or more different kinds of atoms. A chemical reaction is rearrangement of atoms. He assumed things to explain his observations. He was able to calculate relative weightd of particles from his experiment.

  • Thomson

    Thomson
    He discovered the electron and isotopes. He added to what they thought of an atom before. Cathode rays experiment- measures masss of cathode raya showing they were made of particles. They were not atoms, but a subatomic particle was discovered.
    Harvey. "Unit 5, Concept 2." History of the Atom. ZHS, Zachary. 25 Feb. 2014. Lecture.

  • Rutherford -

    Rutherford -
    He thought thatthey must get scattered by tiny bits of postively charged matter. Most of the space around the posivitve centers had nothing in them. He thought that the electrons must exist somewhere within this empty space. Thought that the negative electron orbited a positive center, identifiede particles in nucleus as descrete positive charges. He had the Gold Foill Experiment - which helped describe the nuclear structure of the atom.Harvey. "Unit 5, Concept 2." History of the Atom. ZHS, Zach

  • Bohr

    Bohr
    He said that protons are in the nucleus and electrons surround it. The elcectrons can only move in certain paths and they determine the chemical property. This corresponds to excited electrons fallen to lowest energy level known as the ground level.
    "History of Atoms." History of Atoms. N.p., n.d. Web. 26 Feb.
    2014.
    Harvey. "Unit 5, Concept 2." History of the Atom. ZHS, Zachary. 25 Feb. 2014. Lecture.

  • Heisenberg and Schrodinger

    Heisenberg and Schrodinger
    Heisenberg based his theory on mathematical quantities called matrices that fit with the conception of electrons as particles whereas Schrodinger based his theory on waves.The results of both theories appeared the same mathmatically! Heisenberg said that no experiement can measure the position and momentum of a particle. Scientists calll it the "Heisenberg uncertainty principle."
    "History of Atoms." History of Atoms. N.p., n.d. Web. 26 Feb. 2014.