History of the Atom

By maaack14
  • 400 BCE

    Democritus

    Democritus
    Democritus is know for giving it the name of the "atom." It meant that an object could not be split up anymore when you reached the atom. His ideas were not accepted at his time, because Aristotle called atoms nonsense. Democritus also based most of his works off of observations and curiousity, so there never ever really was an "experiment."

  • John Dalton

    John Dalton
    John Dalton is credited for his atomic theory, which is:
    1. All matter is made up of atoms.
    2. All atoms of an element are identical in mass and properties.
    3. All compounds are combinations of two or more different type of atoms.
    4. A chemical reaction is atoms being rearranged.
    Dalton had based his theory on two laws: the law of conservation of mass and the law of constant composition. Most of his information on this came from observing chemical reactions.
    http://tinyurl.com/po4ngnm

  • Ernest Rutherford

    Ernest Rutherford
    Rutherford was the person who discovered the nucleus. He was experimenting with a piece of gold foil and shooting alpha particles at it. He was expecting it to gostraightthrough every time, although one time it bounced back at him. He concluded from this that all positive charge has to be concentrated in the center of the atom, which was the nucleus.
    http://edtech2.boisestate.edu/lindabennett1/502/rutherford.html

  • J.J. Thompson

    J.J. Thompson
    Thompson is credited for finding the electron in the atom. He discovered this by putting magnets at the end of a cathode ray tube, and the green beam bent from the negative pole and went towards the positive. Thompson concluded from this that the electrical particles had a negative charge.
    http://edtech2.boisestate.edu/lindabennett1/502/thompson.html

  • Niels Bohr

    Niels Bohr
    Bohr is most credited for his atomic model, named Bohr atomic model. It has the nucleus in the middle which will state what the atom is, with circles surrounding it acting as electron clouds. Dots are then placed in the electron clouds to represent the electrons in the atom. Bohr first created this model to use in physics, and didn't apply it to learn more about the atom and periodic table until the early 1920s. There wasn't really an experiment, just a lot of math.
    http://tinyurl.com/jxkrf9h