History of the Atom Timeline by Hope Walls

By hopewalls
  • 450

    Democritus (460 BC)

    Democritus (460 BC)
    Democritus claimed that everything is made up of atoms; that they are physically indivinsible and indestructable, and make up all things. To initially find the atom, Democritus took a seashell and broke it in half. He repeated this process numerous times until he was left with a fine powder. He then took the smallest piece of powder and could not break it. To Democritus, the atom looked like a marble.
    "Models of the Atom Timeline." YouTube. YouTube, 06 Dec. 2012.
    Web. 25 Feb. 2014.
  • 450

    Aristotle (400 BC)

    Aristotle (400 BC)
    Aristotle didn't believe in the Atomic Theory, he believed that all matter was made up of "The Four Elements" which are fire, earth, air, and aether. He didn't have any proof of this theory, and he didn't perform any experiments.
    "Models of the Atom Timeline." YouTube. YouTube, 06 Dec. 2012. Web. 25 Feb. 2014.
    "Aristotle." Aristotle. N.p., n.d. Web. 25 Feb. 2014.

  • Dalton

    Dalton
    Dalton redeveloped the atomic theory. He believed the atom was the smallest unit of matter, but could not be broken down. Dalton had an idea that atoms always combined together in simple whole number ratios or proportions. He thought that the atom looked like tiny balls that arranged in different combinations.
    "Dalton Atomic Theory." Dalton Atomic Theory. N.p., n.d. Web. 25 Feb. 2014.
    YouTube. YouTube, 06 Dec. 2012. Web. 25 Feb. 2014.

  • Thomson

    Thomson
    Thomson found that atoms weren't indivinsible, but made up of smaller particles -electrons, which he discovered using a Cathode Ray tube. He discovered that an atom is a positively charged substance with negatively charged electrons, balancing eachother out. He thought that the atom looked like a sphere of positive force with electrons scattered throughout -Plum Pudding model.
    "Plum Pudding Model." Wikipedia. Wikimedia Foundation, 24 Feb. 2014. Web. 25 Feb. 2014.

  • Rutherford

    Rutherford
    Rutherford discovered the nucleus and that all of the positive charge was concentrated in the center. His theory was that the atom has a positively charged nucleus with negatively charged electrons orbiting around it. He used the Gold Foil experiment to make his discoveries, and created the Nuclear Model which shows a nuclus surrounded by floating electrons.
    "Models of the Atom Timeline." YouTube. YouTube, 06 Dec. 2012.
    Web. 25 Feb. 2014.
    http://upload.wikimedia.org/wikipedia/commons/thumb/e/e

  • Bohr

    Bohr
    Bohr found that the nucleus is in the middle of the atom, but electrons spin around the nucleus in circular orbits, he modified the Rutherford model by requiring that the electrons move in orbits of fixed size and energy. He made the Bohr Model - a nucleas surrounded by electrons that orbit arount it like planets around the sun.
    "Models of the Atom Timeline." YouTube. YouTube, 06 Dec. 2012. Web. 25 Feb. 2014.
    http://astronomy.nmsu.edu/geas/lectures/lecture18/pics/lec18_amod03.png

  • Heisenberg and Schrodinger

    Heisenberg and Schrodinger
    Schrodinger showed that electrons buzz around an atom, creating shapes -orbitals. He came up with the equation for quantum wave mechanics which aided his discoveries. He also created the Quantum Mechanical Model which shows how electrons sketch shapes around a nucleus.
    Heisenberg discovered the uncertainty principle, that the simple act of looking for electrons will change their position or momentum.
    "Where Did Schrödinger Solve the Radiating Problem of Bohr's Model?" Quantum Mechanics. N.p.,