1. Particle Nature of Light
Section 5.1 Continued
Particle Nature of Light

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. 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 Plank’s Constant = x J•s

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

5. Particle Nature of Light
Photoelectric Effect: electrons, called photoelectrons, are emitted from a metal’s surface when light of a certain frequency shines on the surface.
Photoelectrons
Light

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

7. Neon Signs

8. Atomic Emission Spectra
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.

9. Atomic Emission Spectra
Hydrogen (H)
Helium (He)
Oxygen (O)

10. Atomic Emission Spectra
Neon (Ne)
Xenon (Xe)

11. Homework
7-12 on page 126