Atom timeline

By Kenziemccaffrey
  • 400 BCE

    Democritus

    Democritus
    Democtitus created theory that all matter was made of tiny little particles that determine the properties of matter. These particles could be any shape but in between the particles was emptyness.

  • Dalton

    Dalton
    Dalton developed his theory by experiment with water molecules. He ask the question how can water vapor and air could occupy the same space at the same time. He experiment with multiple gases into a mixture to find the gases individual property and the mixture as a hole. He recognize that particles weigh. That told us the weight of the atom didn't change even in a chemical reaction.

  • J.J Thomson

    J.J Thomson
    Thompson discovered the electron. By experimenting with cathode ray, he also studied positively charged neon gas. Thomaon notice the model of the atom during his time accounted for negatively or positively charged particles so he made the plum pudding.

  • Rutherford

    Rutherford
    Rutherford tested Thompson's hypothesis by the gold foil experiment. He used alfa particles that are positively charged. He shot the gold foil with these particles and like he suspected it went through but some got deflected and some slightly. This help Rutherford to discover the nucleus.

  • Bohr

    Bohr
    Bohr was the one who discovered the shell model of the atom. He didn't do a experiment but looked at rutherford. He made the planetary model of the atom that shows atoms orbiting the atom like a planet. He also discovered that that electrons can move up and down the atom's shell. He concluded that if the electron have less energy it would be closer to the atom but if it has more it whould be farther.