1. Acceleration/Radiation Spectral Lines
Problems with the Rutherford Atom
Acceleration/Radiation
Spectral Lines

3. Spectral lines Rydberg’s Formula: (FYI)
Energy from excited atoms
demo
Rydberg’s Formula: (FYI)
1/ = R(1/22 - 1/n2), n = 3, 4, ...(Balmer) (Visible)
1/ = R(1/12 - 1/n2), n = 2, 3, ...(Lyman) (UV)
1/ = R(1/32 - 1/n2), n = 4, 5, ...(Paschen) (IR)
(R = x 10-7 m-1) H He
Sun

4. Bohr’s Quantum Atom
Only certain orbits are allowed “stationary states”
Electron transitions create photons
1/ = R(1/22 - 1/n2), n = 3, 4, ...(Balmer) (Visible)
1/ = R(1/12 - 1/n2), n = 2, 3, ...(Lyman) (UV)
1/ = R(1/32 - 1/n2), n = 4, 5, ...(Paschen) (IR)

5. Example: What is the wavelength of the first Lyman line? (122 nm)
The first Lyman line is a transition from -3.4 eV to eV, so it releases 10.2 eV of energy. A photon with this energy has this wavelength:
E = (10.2)(1.602E-19) = E-18 J
E = hc/λ, λ = hc/E =
(6.626E-34)(3.00E8)/( E-18) =
E-07 m =

6. Limitations of Bohr’s model
Works well for H, but doesn’t even work for He
Did not explain
Spectral fine structure
Brightness of lines
Molecular bonds
Theory was not complete.
But otherwise it generally kicked tuckus

8. 1. What possible photon energies can you get from these energy levels
1. What possible photon energies can you get from these energy levels? (there are 6 different ones) 1 4 9 3 8 5
-5.0 eV
-6.0 eV
-9.0 eV
-14.0 eV
1, 4, 9, 3, 8, and 5 eV

9. 2. What is the wavelength of the photon released from the third Lyman spectral line (from -.85 to eV)?
E = hf = hc/ 
E = = eV
E = (12.75 eV)(1.602E-19J/eV) = 2.04E-18J
 = hc/E = 97.3 = 97 nm
97 nm

10. 3. What is the wavelength of the photon released from the second Balmer spectral line (from –0.85 to -3.4 eV)?
E = hf = hc/ 
E = = 2.55 eV
E = (2.55 eV)(1.602E-19J/eV) = 4.09E-19J
 = hc/E = 487 = 490 nm
490 nm

11. 4. An nm photon is emitted. What is the energy of this photon in eV, and what transition occurred?
E = hf = hc/ 
(6.626E-34)(3.00E8)/(86.4E-9) =
E-18 J
( E-18 J)/(1.602E-19) = 12.1 eV
This could be the second Lyman line
12.1 eV