1. J.j. Thomson Atomic Model
Plum Pudding Model or Blueberry Muffin Model
Proposed in 1904
Negatively charged electrons (raisins or blueberries) are surrounded by a positively charged “pudding” (or muffin)

2. Ernest Rutherford Gold Foil Experiment
Discovery of the atomic nucleus
Rutherford shot alpha particles at a piece of gold foil surrounded by detectors
This suggests that they hit something larger = Nucleus
Gold Foil Video Demonstration
Expected Outcome:
Alpha particle shoots straight through, electrons according to the Plum Pudding Model are not enough to deflect the particles
Real Outcome:
Alpha particles deflected in some instances
This suggests that they hit something larger = Nucleus

3. Ernest Rutherford Atomic Model
Gold Foil experiment marked the discovery that the atom was made up of mostly empty space and contained a positively charged nucleus
Rutherford Model suggests that atoms are unstable

4. Niels Bohr Atomic Model
Proposed in 1913
Atoms are mostly empty space with a positively charged nucleus surrounded by electrons that travel in circular orbits (like the solar system)
Revised Rutherford’s atom to create a more stable model of the atom

5. Present Day Atomic Model
James Chadwick discovered the neutron in 1932
The neutron is a subatomic particle that resides in the nucleus and has no charge
This model says that we can’t know the exact location of the electron but the electrons are more likely to be in specific areas of the atom
This cloud model shows the possible locations of the electrons at any moment