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Atomic Theory Timeline

By Grant Candelaria
  • 300

    Democritus (460BCE-370BCE)

    Discovered atoms. Questioned whether matter could be infinitely divided. He came up with the idea in which there is a point where matter can't be divided any more and named it atomos. This gives us a basis that we can bass as the smallest unit of matter. Mokeur, Professor. "HISTORY OF THE ATOM FROM DEMOCRITUS TO BOHR AND SCHRÖDINGER." HISTORY OF THE ATOM FROM DEMOCRITUS TO BOHR AND SCHRÖDINGER. I. Noels, 2003. Web. 30 Sept. 2013. http://profmokeur.ca/chemistry/history_of_the_atom.htm.
  • 350

    Aristotle (384BCE-322BCE)

    Believed that no matter how many times you split matter it will always become smaller. Helped to reinforce the concept that the atom is the smallest thing that something could be divided into. "HISTORICAL OUTLINE of the Atomic Theory and the Structure of the Atom." HISTORICAL OUTLINE of the Atomic Theory and the Structure of the Atom. Semo, n.d. Web. 30 Sept. 2013. http://cstl-csm.semo.edu/mcgowan/ch181/atomhist.htm.
  • Jan 1, 600

    End of Ancient Greece

  • America Gains Independence

  • Ben Franklin Is Born

  • Joseph Proust (1754-1826)

    Published his Law of Definite Proportions. This states that no matter where you get an element or compound from it is still made up of the same basic building blocks. Gave us information towards the building blocks of compound and/or elements. Damelin, Dan. "Atomic Theory: Joseph Proust." Atomic Theory: Joseph Proust. Dan Damelin, n.d. Web. 30 Sept. 2013. http://www.concord.org/~ddamelin/chemsite/c_AtomicTheory/Proust.html.

  • John Dalton (1766-1844)

    Discovers compounds and atoms. John Dalton's theory remains valid to this day. He discovered that all matter is made up of atoms and all atoms of an element are the same in mass and properties. Also, he discovered that a compound is a combination of two or more atoms. Leon, Prof. N. De. "Dalton's Atomic Theory." Dalton's Atomic Theory. Professor N. De Leon, Spring 2001. Web. 29 Sept. 2013. http://www.iun.edu/~cpanhd/C101webnotes/composition/dalton.html.

  • Henri Becquerel (1852-1908)

    Discovered radioactivity. While he was studying X-rays he discovered that some elements lose electrons over time.
    Buescher, Lee. "Atomic Structure Timeline." Atomic Structure
    Timeline. Watertown High School, 2004. Web. 30 Sept. 2013. http://atomictimeline.net/index.php.

  • Max Planck (1858-1947)

    Published paper that proposed the quantum of action, now know as Planck's constant h. This helped us to understand wave lengths. Soylent Communications. "Max Planck." Max Planck. NNDB, 2013. Web. 30 Sept. 2013. http://www.nndb.com/people/229/000058055/.

  • J. J. Thomas (1856-1940)

    Suggested a model of the atom as a sphere of positive matter and discovered the electron. Helped for people to dive deeper into the atom and look at the electrons and gave another perspective of the atom. "Joseph John Thomson." Homepage of the Chemical Heritage Foundation. Ed. Chemical Heritage Foundation. Chemical Heritage Foundation, n.d. Web. 30 Sept. 2013. http://www.chemheritage.org/discover/online-resources/chemistry-in-history/themes/atomic-and-nuclear-structure/thomson.aspx.

  • Albert Einstein (1879-1955)

    Proved that atoms exist. Use quantum physics to show this. This shows us that the previous scientist were right and we now have a strong base to base our study of atoms on. Ask.com. "How Did Einstein Contribute to the Atomic Theory?" - Ask.com. Ask.com, n.d. Web. 30 Sept. 2013. http://www.ask.com/question/how-did-einstein-contribute-to-the-atomic-theory.

  • Neils Bohr (1885-1962)

    Discovered the nucleus.Neils Bohr contributed greatly to the atomic theory we use today because he discovered the nucleus. He also discovered that the outer ring of electrons lets you determine the element. And he has an element named after him (Bohrium). Palermo, Elizabeth. "Niels Bohr: Biography & Atomic Theory." LiveScience.com. LiveScience, 14 May 2013. Web. 29 Sept. 2013. http://www.livescience.com/32016-niels-bohr-atomic-theory.html

  • WWI Begins

  • Ernest Rutherford (1871-1937)

    Discovered and named the proton. He also was credited for splitting the atom. This helped us pull together the inside of an atom. Also, it showed us that there is indeed something smaller than an atom. Wikipedia. "Ernest Rutherford." Wikipedia. Wikimedia Foundation, 30 Sept. 2013. Web. 30 Sept. 2013. http://en.wikipedia.org/wiki/Ernest_Rutherford.

  • WWI Ends

  • Robert Millikan (1868-1953)

    Wins Nobel Prize for his oil drop experiment. Robert contributed to the atomic theory because he discovered the charge of an electron. He discovered this through his oil drop experiment. Withouut this knowledge we would not know what we do about the atom. Wiki Answers. "What Did Robert Millikan Contribute to the Atomic Theory or Model?" WikiAnswers. Answers, n.d. Web. 30 Sept. 2013. http://wiki.answers.com/Q/What_did_Robert_Millikan_contribute_to_the_atomic_theory_or_model.

  • Louis de Broglie (1892-1987)

    Disproved the solar system theory and says electrons are in waves. Revolutionized the way people thought of the atom. Wikipedia. "Louis De Broglie." Wikipedia. Wikimedia Foundation, 27 Sept. 2013. Web. 30 Sept. 2013. http://en.wikipedia.org/wiki/Louis_de_Broglie.

  • Werner Heisenberg (1901-1976)

    Discovered the movement of electrons. Also helped to develop the quantum mechanical model. This helps us to figure out electron configuration because without this we wouldnt know how the electrons moved. Tangient LLC. "Werner Heisenberg." The-History-of-the-Atom. Tangient LLC, 2013. Web. 30 Sept. 2013. <http://the-history-of-the-atom.wikispaces.com/Werner Heisenberg>.

  • Erwin Schrodinger (1887-1961)

    Took the Bohr model one step futher and created the Quantum Mechanical Model. This helps determine the likelihood of finding an electron in certain positions. Helps us understand the positioning of electrons. ABCTE. "Development of the Atomic Theory." Development of the Atomic Theory. ABCTE, 2007. Web. 30 Sept. 2013. http://www.abcte.org/files/previews/chemistry/s1_p6.html.

  • James Chadwick (1891-1974)

    Discovery of neutrons. Gave us yet another way to look at the atom. We aleady had the elctron and then we got the neutron. "James Chadwick -Atomic Theory." James Chadwick -Atomic Theory. N.p., n.d. Web. 30 Sept. 2013. http://jameschadwickatomictheory.weebly.com/.

  • WWII Begins

  • WWII Ends

  • Vietnam War Begins

  • Vietnam War Ends

  • Roman-Persian War

  • Persian War Begins

  • Persian War Ends