Atomic Model Timeline

Timeline created by jujube1999
  • Dalton Model

    Dalton Model
    In 1808, John Dalton published the New System of Chemical Philosophy. This system explained that each element is made up of atoms. These atoms have a unique mass for each particular element. Dalton thought that atoms were like small, solid balls.
  • Thomson Model

    Thomson Model
    J. J. Thomson proposed a model in which the atom is a postively charged sphere with electrons inside of it. A good way to represent this model is a blueberry muffin. The muffin has blueberries scattered throughout it, similar to the electrons scattered throughout the atom.
  • Nagaoka Model

    Nagaoka Model
    A Japanese physicist named Hantaro Nagaoka created his own model of the atom in 1904. He said that the atom had a large sphere (the nucleus) in the center. This sphere had a positive charge and was orbited by electrons. (similar to the solar system)
  • Rutherford Model

    Rutherford Model
    Ernest Rutherford found that electrons orbit the positively charged nucleus randomly. He also concluded that the atom is mostly empty space.
  • Bohr Model

    Bohr Model
    Niels bohr, a Danish physicist, discovered that electrons are not randomly located around the nucleus. He created a model showing electrons moving in specific layers. He claimed that atoms absorb or give off energy when electrons move from one layer to another.
  • Modern Model

    Modern Model
    In the 1920s, many scientists collaborated to create the current model of the atom. They determined that it is impossible to know exactly where an electron is , and also that electrons form a negatively charged cloud around the nucleus.
  • Chadwick Model

    Chadwick Model
    James Chadwick discovered the neutron. The neutron is a particle that has no electrical charge and about the same mass as the proton. Once Chadwick discovered the neutron, it was clear why atoms were heavier than the total mass of their protons and electrons.