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The Dalton Model
John Dalton proposed that elements consist of atoms that are identical, have the same mass and that compunds are atoms from different elements combined together, He established that atoms are the building blocks of matter and that they are indivisible. -
The J.J. Thompson Model
J.J. Thompson proposed that atoms consist of electrons which are over 1000 times smaller than the atom. His model shows the atom having both negatively and positively charged subatomic particles. His model is nicknamed "the raisin bread model" and "the plum pudding model." Thompson's work disproved Dalton's theory that atoms are indivisble. -
The Rutherford Model
Ernest Rutherford conducted the "gold foil" experiment where he observed alpha particles passing through gold foil. As expected most particles passed through. However, a few particles were deflected back. He concluded that the atom is 99.99% emprty space, that the nucleus contains a positive charge and most of the mass, and that the nucleus is approximately 100,000 times smaller than the atom. -
The Bohr Model
Neils Bohr's model of the atom, also called the solar system model, updated the Chadwick model by placing the electrons in an orbital ring around the nucleus. The electrons can transfer from ring to ring but can't travel in between rings. The different rings also have different energy levels. -
The Modern Model
The modern model,from the works of scientists Heisenberg and Schrodinger, is based on the principle of uncertainty of electron movement. Rather than moving inside rings, the electrons orbit in a wave like patternHeisenberg, Schrodinger around the nucleus. Some refer to these waves as "electron clouds." This model is also built upon the concepts of quantum theory and sub-sub atomic particles. -
The Chadwick Model
In 1932, James Chadwick confirmed Rutherford's suggestion that a neutral subatomic particles exist. This subatomic particle was called the neutron. It was noted that neutrons contain mass and are found in the necleus, along with protons. The discovery of the neutron was very important in the field of chemistry and played an important role in neclear fission and the splitting of an atom.
