Download Chp.23 Outline - Redlands High School

Chapter 23 Atomic Physics
Lecture Questions:
1) What is a photon? Do all photons have the same energy? What is a quantum
value? Give some examples of other quantum values besides the photon. Write
the equation relating the frequency of a photon to its energy. Does a photon fit
better in the particle or wave nature of light? What does an electron volt measure?
How many Joules are in an electron volt?
2) What is a blackbody? As the temperature of a blackbody increases what does
classical mechanics predict for the intensity of different wavelengths of EM
radiation that are emitted from a blackbody? Draw the actual intensitywavelength curve of a blackbody. How did Planck resolve the ultraviolet
catastrophe? Write the formula relating the frequency of a photon to its energy.
3) Describe the photoelectric effect. Explain why light below the threshold
frequency will not cause photoelectrons to be released no matter how bright its
intensity. What will happen if the intensity of a light above the threshold is
increased? What happens if the frequency of the light is increased? Define work
function. Write the equation relating the kinetic energy of the photoelectrons to a
metal’s work function and the energy of the photons hitting it. List some uses of
the photoelectric effect.
4) Describe Compton’s observation about the momentum of photons after they
collide with electrons. Would you ever see an increase in the energy of a photon
after the collision? If so, when?
5) List some examples of phenomena that show the particle nature of light. List
examples of phenomena that show the wave nature of light? When does light act
like a particle? How about a wave?
6) In 1924 what did Louis DeBroglie propose about matter in his doctoral thesis?
Why isn’t the wavelike nature of megascopic objects observed? Write the
equation for the DeBroglie wavelength of an object.
7) Describe the Bohr model of the atom. What phenomena was this model able to
explain?
8) Explain the cause of spectral lines produced by an excited gas. What does the
color of each line depend upon? Why does each element have its own set of
spectral lines?
9) Is an electron more wavelike or particle like? Use this to explain why electrons
can only exist at certain distances from the nucleus of an atom.
10) State the Heisenberg uncertainty principle. How does this rule change the Bohr
model of the atom?
Practice Problems:
1) Yellow light with a frequency of 6.0x1014 Hz is the predominant frequency in
sunlight. In units of the eV, what is the energy carried by one photon of this
light?
2) A quantum of a certain color of visible light is found to have an energy of
5.0x10-19Joules. What is the frequency of this light?
3) A vibrating mass spring system has a frequency of 0.56 Hz. How much energy of
this vibration is carried away in a one quantum change?
4) Radiation emitted from human skin reaches its peak at =940m. A) What is the
frequency of this radiation? B) How much energy is carried in one photon of
these waves?
5) Which of the following metals will exhibit the photoelectric effect when light of
7.0 x 1014 Hz is shined on it? A) lithium hft = 2.3eV B) silver hft = 4.7eV C)
cesium hft = 1.9eV
6) For the metals listed above what is the maximum KE of the photoelectrons?
7) Light of the wavelength 350 nm falls on a potassium surface, and the
photoelectrons have a maximum KE of 1.3 eV. What is the work function of
potassium? What is the threshold frequency of potassium?
8) Calculate the de Broglie wavelength of an electron(m=9.109 x 10-31 kg) moving at
1.00 x 107 m/s.
9) If the de Broglie wavelength of an electron is equal to 5.00 x 10-7 m, how fast is
the electron moving?
10) A bacterium moving across a petri dish at 3.5m/s, has a de Broglie wavelength
of 1.9 x 10-13 m. What is the bacterium’s mass?
Schedule:
Day:
Monday
Tuesday
Wednesday
Thursday
Class Activity:
Lab: Quantum Stations
Lecture: Waves behaving like particles
Lecture: Particles behaving as waves
Homework Review
Friday
Chapter 23 Quiz
Homework Due:
None
None
None
Chp. 23 Qs. 1-13,14,16,18,
20-38, 40, 42
Notebook