Chapter 15 Review

Video Review

Key Concept Summary

TA Summary


Describes the likelihood of detecting a particle as it travels through space
The more you know about position the less you can know about momentum, and the more you know about momentum the less you can know about position.
Phenomenon that creates areas of high probability where the electron will strike the screen
Phenomenon that creates areas of low probability where the electron is unlikely to strike the screen
Postulates a universe where actions do not lead to pre-determined effects
The physical world continues on a predetermined course once set in motion.
Alternating bands of regions where lots of electrons shot at closely spaced slits hit a screen followed by regions where no electrons hit the screen.


The uncertainty principle states that the more you know about position, the more you know about momentum.
Matter has both wave and particle properties.
Electrons can form interference patterns, just as light can.
It is impossible to predict exactly where an electron will strike the screen after passing through two slits in a double-slit experiment.
An object's momentum is the only property associated with probability waves.
If moving slowly enough, small objects can have wavelengths that reach macroscopic dimensions.
After passing many electrons through two slits, an interference pattern on the screen looks like the probability curve below.


If the speed of a particle increases, its wavelength
Which of the following could NOT be caused to form a diffraction pattern?
For which phenomenon would the Heisenberg Uncertainty Principle be a significant consideration in describing motion?
Macroscopic objects don't show interference effects because
The Heisenberg Uncertainty Principle seems to conflict with the concept of
Electrons passing one at a time through a two-slit apparatus strike a screen. The resulting pattern on the screen after many electrons have struck the screen is
If electrons orbit the nucleus of an atom, as the Bohr model suggests which of the following events should happen, but doesn't?
Which of the following electrons would have a larger wavelength?
An electron an a proton both have the same momentum, which has the larger wavelength?
Why don't we observe wave behavior in macroscopic objects like baseballs?
How does the wavelength of an electron compare to the wavelength of electromagnetic waves?
What is the smallest object you could see with an electron microscope?
By designing better and better instruments, it is possible to continue to improve the accuracy of measurements of the position of an electron indefinitely.
By designing better and better instruments, it is possible to continue to improve the accuracy of measurements of an electrons trajectory (path through space as a function of time) indefinitely.
The three dimensional wave function for an electron with quantum numbers n=2 and l=1 is depicted below. Dark regions are regions of high probability, where light regions are regions of low probability. What does this wave function mean?A depiction of a dumbell-shaped orbital with two lobes.
Which of the following is a consequence of the Pauli exclusion principle?

Free Response

  1. Explain how the double-slit experiment can show both the particle and wave nature of matter.
  2. A proton has a mass that is about 2,000 times as large as the mass of an electron. If a proton and an electron are traveling the same speed, which one will have the larger wavelength?
  3. In an experiment called the Stern-Gerlach experiment, a silver atom passing through a magnet will either bend up or bend down. Quantum mechanics can be used to predict the probability of it going up or down, but not what a single atom will do on a trip through the magnet. What experiment could you do to test whether the probabilities predicted by quantum mechanics are correct?
  4. Very slow neutrons can have wavelengths as long as a millimeter. Use the Heisenberg Uncertainty Principle to explain what a beam of these neutrons will look like after passing through a hole a few millimeters in diameter.
  5. How does the wavelength of an electron in an atom compare to an electron which is moving much faster in a particle accelerator?
  6. Can a single proton interfere with itself? Why or why not?
  7. Your friend argues that she has no choice in her life because the Heisenberg Uncertainty Principle guarantees that everything in this life is random. How would you respond to her?
  8. Physicists have recently been able to slow down beams of atoms so that their wavelengths are macroscopic in size. Under these conditions would it be possible to see interference effects with this beam of atoms? Why or why not?