1. Quantized Energy and Photons
Section 6.2
Quantized Energy and Photons

2. Objectives Compare the wave and particle models of light.
Define a quantum of energy and explain how it is related to an energy change of matter.
Contrast continuous electromagnetic spectra and atomic emission spectra.

3. Key Terms
Quantum
Planck’s Constant
Photoelectric effect

4. More Than Just a Wave Wave model fails to explain several phenomena:
Blackbody radiation
Photoelectric effect
Line spectra

5. Phenomenon #1

6. Blackbody radiation (Planck)
Heated solids emit radiation
Red stovetop
White light bulb
Wave theories did not explain relationship between temperature and wavelengths

7. Particle Nature of Light
Besides having wave characteristics, light also acts like a particle.
The Quantum Concept: Energy can only be gained or lost in a specified amount  A Quantum
Equantum = hv
h is Planck’s Constant = x J•s

8. Blocks and Quanta
Think of energy transfer like building a wall of Legos®.
Only add or take away 1 Lego.
There is no such thing as a ½ Lego.

9. Phenomenon #2

10. Photoelectric Effect (Einstein)
Electrons, called photoelectrons, are emitted from a metal’s surface when light of a certain frequency shines on the surface.
Light
Photoelectrons

11. The Photon Photon: particle of electromagnetic radiation no mass
carries a quantum of energy
Ephoton = hv

12. Phenomenon #3

13. Line Spectra (Bohr) Electricity passed through a tube of gas
Gas atoms absorb energy and become excited
Atoms release the energy absorbed in the form of light.
Each atom has specific frequencies it will release in the light form.

14. Line Spectra Hydrogen (H) Helium (He) Oxygen (O)

15. Line Spectra Neon (Ne) Xenon (Xe)

16. Neon Signs

17. Assignment
Particle Nature of Light Worksheet