1. The Atom http://www.pond5.com/stock-footage/68580/atom5.html
(Chapter 9)

2. Student Learning Objectives
Describe the structure of the atom
Recall the defining properties and behavior of an atom
Apply the dual nature of light to atoms
Analyze the quantum nature of the atom

3. What are the defining properties of regular atoms?
Regular, neutral atoms have an equal number of electrons, protons, and neutrons.
What makes each atom unique is the number of protons.
Ions = electrons lost or gained
Isotopes = different number of neutrons

4. Practice Where is most of the mass in an atom?
What contributes most to the size of an atom?
What is an ion?
Nucleus
Electron orbits
Electric force – electrons repelling
Electrons can be lost or gained

5. More Practice
Use your knowledge of what an ion is, to determine what an isotope is.
Since atoms are mostly empty space, why can’t we walk through walls?

6. What is meant by the dual nature of light?
Quantum theory predicts that objects emit individual packets of energy (photons).
Sometimes light behaves as a wave (wavelengths) and sometimes light behaves as a particle (photons).
Wave-Particle Duality
Half way down link page

7. Wave vs Particle
Particle properties are exhibited under conditions of emission and absorption of light.
Wave properties occur under conditions of reflection and refraction of light.
Image Credit: Tutorvista.com

8. de Broglie Wavelengths
All subatomic particles exhibit wave-particle duality.
Electron orbits set up standing waves.
lDB = h . mv

9. How do atoms emit and absorb light?
Each atom has its own unique pattern of allowed orbits, based on the number of protons.
When electrons change orbits, light is emitted or absorbed.
Image Credit: Wikipedia

10. Image Credit: Openstax
Energy States
The farther an electron is from the nucleus, the higher its energy level.
Ground State: electrons occupy lowest energy levels
Excited State: electrons in added energy levels (infinite)
Image Credit: Openstax

11. Each type of atom emits its own specific pattern of photons.
Atomic Spectrum

12. Image Credit: Openstax

13. E(ni) – E(nf) = E(photon)
Photon Energy
Each photon has a particular energy, based on the quantum jump.
E(ni) – E(nf) = E(photon)
Each color of light has a particular energy per photon.
h = 6.63 x Js
E = hc l
E = hn

14. Practice
What is the energy of a photon that results from the 4  2 transition in the hydrogen atom?
What is this energy in Joules?
1 ev = 1.6 x 10−19 Joules
Hydrogen Orbit eV
n = 1 8
n = 2 15
n = 3 30
n = 4 80

15. More Practice
What is the energy of one yellow photon (l = 517 nm) from the Sun?
How does the energy of a single photon from the Sun compare to the total energy output of the Sun (4 x 1026 Watts)?
Image Credit; NASA