1. Light l The study of light led to the development of the quantum mechanical model. l Light is a kind of electromagnetic radiation. l Electromagnetic radiation includes many types: gamma rays, x-rays, radio waves… l Speed of light = 2.998 x 10 8 m/s, and is abbreviated “c” – w use 3.00 x 10 8 l All electromagnetic radiation travels at this same rate when measured in a vacuum

2. R O Y G B I V Frequency Increases Wavelength Longer IB: visible light = 400-700 nm

3. Parts of a wave Wavelength Amplitude Origin Crest Trough

4. Equation: c = c = speed of light, a constant (3.00 x 10 8 m/s) (nu) = frequency, in units of hertz (hz or s -1 ) (lambda) = wavelength, in meters Electromagnetic radiation propagates through space as a wave moving at the speed of light.

5. Wavelength and Frequency l Are inversely related As one goes up the other goes down. l Different frequencies of light are different colors of light. l There is a wide variety of frequencies l The whole range is called a spectrum

6. Radio waves Micro waves Infrared. Ultra- violet X- Rays Gamma Rays Low Frequency High Frequency Long Wavelength Short Wavelength Visible Light Low Energy High Energy

7. Long Wavelength = Low Frequency = Low ENERGY Short Wavelength = High Frequency = High ENERGY Wavelength Table

8. The Math l There are 3 equations: c = E = h Wave # = 1/ (cm) l Know these!

9. 1a.

10. Examples 1) What is the wavelength of blue light with a frequency of 8.3 x 10 15 hz? 2) What is the frequency of red light with a wavelength of 4.2 x 10 -5 m? 3) What is the energy of a photon of each of the above?

11. Ionization Energy l the amount of energy required to remove 1 mol of electrons from the ground state of 1 mol of the gaseous atom. X(g)  X + (g) + e -

12. Ionization Energy IE increases for successive ionizations

13. Ionization Energy

15. Limit of convergence – where the energy levels merge Forms a continuum. (basically around n=∞) (ionization has occurred) 1 st IE The frequency at the line of convergence can help calculate IE 1.

16. Ionization Energy

17. Examples 4. H has a 1 st IE of 1312 kJ/mol. Calculate the wavelength (nm) for the limit of convergence observed in the line spectrum. 5. The convergence limit for He is 50.5 nm. Calculate the 1 st IE of He in kJ/mol.