1. Atomic Models Main Concept:
As is the case with all scientific models, any model of the atom is subject to refinement and change in response to new experimental results. In that sense, an atomic model is not regarded as an exact description of the atom, but rather a theoretical construct that fits a set of experimental data.

2. History of Atomic Models
Evidence Model How This Replaced
Older Model
John Dalton ↓
JJ Thomson
Ernest Rutherford
Neils Bohr
Erwin Shrödinger **
**it is ESPECIALLY important you understand the evidence leading to the refinement between

3. - Scientists use experimental results to test models
- if experimental results ≠ predictions of a scientific model, model must be revised/replaced with a new model able to predict/explain experimental results
- robust scientific models can be used to explain/ predict numerous results over a wide range of experimental circumstances

4. - construction of a shell model through ionization energy data shows how a model can be refined and changed as additional information is considered

5. Dalton Thomson Law of Multiple Proportions
Billiard Ball Model – a simple, indivisible
sphere
Thomson
Cathode Ray Experiment
Plum Pudding Model – existence of electrons

6. Rutherford Bohr Gold Foil Experiment
Rutherford Model – existence of a nucleus
Bohr
Use of hydrogen spectra
Bohr Model – existence of electron shells

7. Problems with the Bohr Model
- Not all of the spectra
could be correctly
predicted for larger atoms
and couldn’t explain certain
spectra
- Contradicted Heisenberg’s Uncertainty Principle; it assumed knowledge of both location and momentum

8. What does the QM model address?
- The dual nature of the electron (as a particle and a wave)
- Correctly predicts spectra
- Allows for probability waves in agreement with Heisenberg’s Uncertainty Principle
- Consistent with periodic models, data, and trends

9. Schrödinger Mathematical Wave Modeling explain observed phenomenon
Quantum Mechanical Model – current model