Download Double-Slit Experiment

Chapter 7
Atomic Structure and Periodicity
Name
Any day you don’t have this, or need new copy, it’s -5 from exam
7.1 Electromagnetic Radiation
Cosmos: A spacetime odyssey
“Hiding in the light”- 25:53
“Sisters of the sun” – 7:55-20:55, 30, 33:50Double-Slit Experiment: (YouTube: “Dr. Quantum: Double Slit
Experiment”
Nature of particles (draw bands):
Nature of waves (draw interference pattern)
Electron:
1-slit:
2-slit:
What happened? Explain the follow-up experiments:
1
Explain analysis and conclusion:
The act of observing – what does the observer do?
HW 1: For Wednesday, find research on the dual nature of the
electron; source can be electronic, but it must be from a science
journal or magazine (whose article cites credible research) –
- 20 pts, summary of experiment, in your own words
- Proper citation
- Names of scientists
- Results and Implications of results
2
Nature of waves:
Wavelength:
Amplitude:
Frequency:
Speed of light:
c=
Examples of waves:
a.
b.
c.
3
Example 1: Frequency of electromagnetic radiation:
Red colors in fireworks are due to the emission of light in
wavelengths around 650 nm, and salts with the strontium metal, like
strontium nitrate or strontium carbonate, are used for this. Calculate
the frequency of red light of wavelength 6.50 x 10^2 nm.
Equation:
Constant:
Nature of Light
Range (wavelength and frequency):
Visible light:
4
7.2 Photoelectric Effect
Planck’s Constant:
Equation:
Variables:
Example 2:
Blue color in fireworks is achieved by heating copper (I) chloride to
about 1200 degrees C. The compound emits blue light with
wavelengths of 450 nm. What is the increment of energy (the
quantum) emitted at 4.50 x 10^2 nm by CuCl?
Equation 1:
Equation 2:
Planck’s Constant:
5
Conclusions from Einstein and Plank:
Energy is quantized. It can occur only in discrete units called
______________.
de Broglie:
Corrected equation to account for relationship between mass and
wavelength:
m=
de Broglie equation:
Example 3
Compare the wavelength for an electron (mass = 9.11 x 10^-31 kg)
traveling at a speed of 1.0 x 10^7 m/s with that of a ball (mass = 0.10
kg) traveling at a speed of 35 m/s.
Use λ = h/mv
Constant:
For electron:
λ=
For ball:
λ=
CONCLUSION:
6
HOMEWORK:
Textbook:
p.342-343
19.
40.
42.
44.
45.
51.
7
7.2 Photoelectric effect
When electrons are emitted from the surface of a metal when light
strikes it. The following are characteristics and details of this
phenomenon:
1. Studies in which the frequency of the light is varied show that
NO electrons are emitted by a given metal below a specific
threshold frequency, v0 .
2. For light with frequency lower than the threshold frequency, no
electrons are emitted regardless of the intensity (amplitude)
3. For light with frequency greater than threshold frequency, the
number of electrons emitted increases with intensity of light
4. For light with frequency greater than threshold frequency, the
kinetic energy of the emitted electrons increases linearly with
the frequency of light
*Takeaway? What is “threshold frequency”?
E = mc2
This equation means?
m=
Conclusions from Einstein and Plank:
Energy is quantized. It can occur only in discrete units called
______________.
de Broglie:
Corrected equation to account for relationship between mass and
wavelength:
8
m = h/λv
and therefore
λ = h/mv
Example 3
Compare the wavelength for an electron (mass = 9.11 x 10^-31 kg)
traveling at a speed of 1.0 x 10^7 m/s with that of a ball (mass = 0.10
kg) traveling at a speed of 35 m/s.
Use λ = h/mv
Constant:
For electron:
λ=
For ball:
λ=
CONCLUSION:
9
Heisenberg Uncertainty Principal
7.3 Atomic Spectrum of Hydrogen
White Light Emission Spectrum:
Sodium and hydrogen Emission Spectrum:
10
Continuous spectrum
Line spectrum
7. 4 Bohr model
Quantum model of the hydrogen atom:
Calculated:
Straight line nature of particle motion:
What effects curved motion?
Curved (accelerated) motion means that electron should do what?
= ASSUMPTIONS BASED IN CLASSICAL PHYSICS!!!
Quantum physics:
11
1. Angular motion of electron (mass, velocity, and orbital radius)
occurs at certain increments
2. Only certain electron energies are allowed in the hydrogen
atom
Energy levels available to the hydrogen atom expressed in new
energy equation, where “n” correlates to an energy level.


 1 
En   2.178 10 18 J  2 
n 
n is an integer, and must be 1, 2, 3, etc.
n increases as the orbit radius increases
n = principal quantum number
ENERGY TRANSITION LEVELS
12
- Note that it takes much more energy to get from “ground” state
to the next orbital distance, than it does to jump from 2nd level to
3rd, 3rd to 4th, etc.
Ground state:
13
Limitations to Bohr model:
7.5 Quantum Mechanical Model of the Atom
Standing wave:
Draw figure 7.11 p311:
Heisenberg Uncertainty Principal:
Draw Figure 7.12 on p312:
14
Schroedinger:
Orbitals
15
Quantum Numbers:
1.
2.
3.
Vocabulary:
Nodes:
Quantum numbers:
Subshells
16
S orbital
p orbital
d orbital
valence electrons
electron configurations
7.8 Electron Spin and Pauli Exclusion Principal
7.11 Aufbau Principal-
H:
Li:
17
B:
7.12 Ionization Energies
Ionization energy :
Trend:
Electron Affinity:
Trend
Atomic Radius
Trend:
18