1. Bohr Model Of Atom

2. Spectrum
Continuous spectrum is the rainbow of colors containing all wavelengths
Line spectrum contains only certain colors or wavelengths
When gases are given energy, they emit line spectra which are characteristic of that gas

3. Continuous Spectrum
Line Spectrum of Hydrogen

4. Niels Bohr Said electrons occupy the atoms in quantized energy levels
Each level (orbit) is assigned an integer (n) called the principal quantum number
As n increases, the radius of orbit is greater

5. Energy Energy of the electron depends on the level it occupies
En = - RH ( 1/n2)
RH is called the Rydberg constant
RH = 2.18x10-18 J

6. When electrons occupy the lowest possible energy level, they are in ground state
When in higher levels, they are in excited state

7. Hydrogen Line Spectrum
H atom absorb a quantum of energy
Energized electron “jumps” to a higher level
When it falls back down, it gives off energy as a photon of light
The frequency of the light depends on the levels it falls from and to

8. Equation ΔE = Ef – Ei hν = RH ( 1/nf2 - 1/ni2)
frequency of light given off depends on the level transition

9. Example 1
Calculate the frequency and wavelength of light given off when an electron in a H atom falls from n=4 to n=2. What color is it?

10. Ionization of Energy
Energy that would be needed to completely remove the electron; make it go from n = 1 to n = ∞

11. Example 2
Calculate the energy required to ionize an electron from the ground state.