1. Electromagnetic Spectrum The emission of light is fundamentally related to the behavior of electrons.

2. Properties of Light Visible light is a kind of electromagnetic radiation A form of energy that exhibits wavelike behavior All the forms of electromagnetic radiation form the electromagnetic spectrum

3. Wave Features Wavelength (λ): The distance between corresponding points on adjacent waves Units are metric units of length. Commonly nm.

4. Wave Features Frequency (ν): The number of waves that pass a given point in a specific time. Unit = Hertz (Hz) = 1/s = s -1

5. Calculations c = λν Wavelength Frequency Speed of light λ c ν = Rearrange to solve for frequency and wavelength: ν c λ =

6. Example Calculation Problem: Given the speed of light = 3.0 x 10 8 m/s, calculate the wavelength of the electromagnetic radiation whose frequency is 7.500 x 10 12 Hz. Solution: ν c λ == 7.500 x 10 12 Hz 3.0 x 10 8 m/s = 4.0 x 10 -5 m

7. Max Plank Found that there is a direct relationship between energy and frequency. Plank’s constant h = 6.626 x 10 -34 J· s E = hν Plank’s Constant frequency Energy

8. Plank and Einstein Quanta: How much energy can be lost or gained by an electron Photon: A particle of electromagnetic radiation carrying a quantum of energy. Light has properties of both particles and waves!!!!!

9. Line Emission Spectra A series of specific wavelengths of emitted light created when the visible portion of light from excited atoms is shined through a prism.

10. Visible Spectrum ROY G BIV

11. Atoms and Their Energy Ground State: The lowest energy state of an atom Excited State: A state in which an atom has a higher energy than it has in its ground state

12. Atoms and Their Energy When an excited atom returns to its ground state, it gives off energy it gained in the form of electromagnetic radiation.

13. Hydrogen Line Spectrum When the visible portion of the emitted light is passed through a prism, it is separated into specific wavelengths.

14. Bohr Model Based on the wavelengths of hydrogen’s line emission spectrum, Bohr calculated the energies that an electron would have in the energy levels for a hydrogen atom.

15. Bohr Model Calculations The energy of each photon is calculated by subtracting the energy of the ground state from the energy of the excited state. These energies correspond to specific wavelengths of the electromagnetic spectrum.