History of the Atom

By codekirk
  • Period: 435 BCE to

    History of the Atom timespan

  • 430 BCE

    Aristotle

    Aristotle
    He believed that everything was made up of one of four things: earth, fire, air, or water
  • 430 BCE

    Democritus

    Democritus
    He discovered/came up with the idea of the atom, and how it is infinitely indivisible into smaller parts.

  • Dalton

    Dalton
    He believed that each element is made up of indivisible atoms, but that point is no longer true; they can divide up into protons, neutrons, and electrons. Chemical compounds are formed when atoms of different elements combine with each other. A given compound always has the same relative number and types of atoms. Chemical reactions are created when the atoms reorganize.

  • Thomson

    Thomson
    He discovered the electron by using a cathode ray tube. He made a model called the plum pudding model; he proposed that atoms have a structure similar to a plum pudding, which had tiny negative-charged electrons embedded in a positively-charged substrate. https://www.youtube.com/watch?v=lLwnACfo7hY (1:50-3:05)

  • Rutherford

    Rutherford
    He discovered that atoms contained a nucleus through the gold foil experiment. He also discovered/proved that the nucleus only contains protons and neutrons. https://www.youtube.com/watch?v=XBqHkraf8iE

  • Bohr

    Bohr
    Bohr's theory goes along with Rutherford's theory. Another name for Bohr's model is the Planetary Model because of the electrons orbiting around the nucleus (that contains protons and neutrons).

  • Modern Atomic Theory

    Modern Atomic Theory
    Our current model is called the Electron Cloud Model. It is different than the Bohr's model because this model says we can't know the exact location of an electron at any given time, while the electrons in the Bohr's model is assigned to specific shells/rings outside the nucleus.