Quantum Mechanics and Atomic Physics Review – Flashcards
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Which of the following phrases correctly describes a blackbody?
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perfectly absorbs and emits all radiation
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Classical electromagnetic theory predicted that the energy radiated by a blackbody would become infinite as the wavelength of the radiation became shorter. What was the contradiction between observation and this result called?
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the ultraviolet catastrophe
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Which of the following statements is true about the energy of a quantum of radiation?
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Energy increases with frequency
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Which of the following statements correctly describes the Compton shift that occurs when photons scatter from electrons?
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Photon wavelengths lengthen as they lose energy to electrons.
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What did Rutherford's experiment demonstrate?
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The atomic nucleus was a small, compact region of positive charge and the electrons moved around the nucleus like planets orbiting the sun.
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What observation was NOT explained by the Rutherford model of the atom?
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The Compton shift, emission spectra, the photoelectric effect, and blackbody radiation
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Which of the following statements is true about an emission spectrum?
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It consists of narrow bright lights.
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What type of spectrum is observed in the light from the sun and other stars?
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an absorption spectrum
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Which of the following is a feature of the Bohr model of the atom?
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Only specific electron orbits with given energies are stable.
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At what point do photons behave less like waves and more like particles?
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as the frequency of the photons increases
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Which of the following experiments indicated that matter waves exist?
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the diffraction of electrons by a single crystal
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Which of the following statements correctly describes the results of simultaneous measurement of momentum and location for a particle?
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The more accurately one quantity is measured, the less accurately the other quantity is known
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What term is used to describe a perfect radiator and absorber of electromagnetic radiation?
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blackbody
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What were the units of light energy emitted by blackbody radiation originally called?
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quanta
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According to the Rutherford model, what makes up most of the volume of an atom? (The nucleus is a very small, positively charged part of the atom.)
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empty space
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In Rutherford's experiment, why did the nucleus repel alpha particles?
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electrostatic repulsion between the positively charged nucleus and alpha particles
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What is the concentration of positive charge and mass in Rutherford's atomic model called?
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nucleus
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Which statement about Rutherford's model of the atom is NOT correct?
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The model explains spectral lines.
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When a high potential difference is applied to a low-pressure gas, what kind of spectrum will the gas emit?
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emission
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Which statement about emission spectra is correct?
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All of the lines result from discrete energy differences.
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What would you observe if light from argon gas were passed through a prism? (emission spectra)
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a series of discrete bright lines
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Which of the following is NOT a feature of Bohr's model of the atom? (The higher energy levels are separated by smaller amounts in diagrams.)
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Electrons emit radiation continuously while orbiting the nucleus.
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What is the process in which an electron returns to a lower energy level and emits a photon? (This is what causes the bright lines in the emission spectrum.)
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spontaneous emission
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How will light behave in a single experiment, according to the principle of wave-particle duality?
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Light will act either like a wave or like a particle.
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Which of the following processes is more easily observable for light with a short wavelength?
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the photoelectric effect
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According to the Heisenberg uncertainty principle, which of the following statements about the simultaneous measurements of position and momentum is true?
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The more accurately one value is measured, the less accurately the other value is known.
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What happens as the frequency of photons increases?
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The wave effects of light become more difficult to observe.
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What picture of the electron is suggested by the quantum-mechanical model of the hydrogen atom?
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a probability cloud
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What does the peak of a probability curve for an electron in an atom indicate?
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the distance from the nucleus at which the electron is most likely to be found
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What is an emission spectrum?
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A series of spectral lines emitted by an atomic gas when a voltage is applied
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Which model of light best explains interference phenomena?
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wave model
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Which model of light best explains the photoelectric effect?
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particle
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The maximum kinetic energy of the photoelectrons emitted by a metal exposed to light of a given wavelength happens to be equal to the work function of the metal. How does the energy of the incoming photons compare to the maximum kinetic energy of the emitted photoelectrons?
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the energy of the incoming photons is equal to twice the maximum KE of emitted photons
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for a photoelectron to be emitted by a metal exposed to photons, the energy of the photons must be greater than its work function (measured in eV)
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work function
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What is the work function of photons -- work function of metals?
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KE = hf - hf(t)
