The Greek Model- 400 BC
Democritus' theory was that atoms are small objects that cannot be divided, created, or destroyed. He believed that atoms are constantly moving. He also believed that different types of matter are made from different atoms. The properties of the atoms he believed were determined by the properties of matter.
The Billiard Ball Model- 1802
Dalton, like Democritus believed that all matter is made from atoms that cannot be divided, created, or destroyed. He believed that suring a chemical reaction that atoms of one element cannot convert into one atom of another element. He said that atoms of one element are identical but are different from atoms of another element. He believed that atoms could only combine in specific ratios
Plum Pudding Model- 1897
Thompson discovered that the atom wasn't a solid ball because there was negatively charged particles, electrons, in the atm along with the positive protons. He called it the Plum Pudding Model because the electrons are like the chocolate chips in a cookie, while the protons make up the rest of the cookie as the "dough" or "pudding".
Planetary Model- 1909-1911
Rutherford discovered that the atom has a positive nucleus in the center along with negative electrons that orbit it. He discovered all of this through The Gold Foil Experiment. In which he would fire positive alpha protons at a sheet of gold foil. The particles would either go through the foil or bounce off into a different direction.
Bohr's Atomic Model- 1913
Bohr discovered that subatomic particles move around the nucleus in a circular orbit. He also found that if energy gets added to an electron then it will move farther away from the nucleus and to a higher electron level. If energy gets taken away from an electron then it will move closer to the nucleus and be on a lower electron level.
Erwin Schrodinger & Louis de Broglie
Electron Cloud Model- 1923 & 1930
The Electron Cloud Modle is the modern atomic modle. Schrodinger discovered that there were waves of electrons which to find the exact location which created a long and complicated calculation. Broglie wrote a thesis about the Quantum Theory that was confirmed to be true by the discovery of the electron.