1. Development of Quantum Mechanics Bohr’s Contribution
AP Chemistry by
Diane Paskowski

2. Questions to Consider
Why do the different chemicals give us different colors? 
Why do we get colors at all?
7.1

3. Atomic Spectrum of Hydrogen
Continuous spectrum – contains all the wavelengths of visible light
Line spectrum – each line corresponds to a discrete wavelength:
Hydrogen emission spectrum
7.3

4. Significance?
Only certain energies are allowed for the electron in the hydrogen atom.
Energy of the electron in the hydrogen atom is quantized.
7.3

5. Bohr Model
Electron in a hydrogen atom moves around the nucleus only in certain allowed circular orbits.
ΔE = ×10-18J[(1/nfinal2)-(1/ninitial2)]
Where n is the energy level
(principal quantum number)
7.4

6. Electronic Transitions in the Bohr Model for the Hydrogen Atom
7.4

7. Figure 7.7 A Change Between Two Discrete Energy Levels Emits a Photon of Light

8. Line Spectrum Of Hydrogen
try/flash/linesp16.swf

9. Bohr Model
Bohr’s model is fundamentally incorrect. This model only works for hydrogen.
Electrons do not move around the nucleus in circular orbits.
7.4