Bohr’s Model of the Hydrogen Atom
| Practice 4.1.1 |
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| A hydrogen atom makes a transition from the n = 3 level to the n = 2 level. It then makes a transition from the n = 2 level to the n = 1 level. Which transition results in emission of the longest-wavelength photon? |
| A. the first transition |
| B. neither, because the wavelengths are the same for both transitions |
| C. the second transition |
| Practice 4.1.2 |
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| Which of the following observations led Bohr to formulate his model of the hydrogen atom? |
| A. Neutrons form a diffraction pattern when scattered from a nickel crystal. |
| B. Electrons are observed to have wave nature. |
| C. A low-density gas emits a series of sharp spectral lines. |
| D. The peak of blackbody radiation moves to shorter wavelengths as temperature increases. |
| Practice 4.1.3 |
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| What was Bohr’s quantum condition on the orbital energies in an atom? |
| A. Angular momentum is quantized. |
| B. Electron acceleration is quantized. |
| C. Electron energy is quantized. |
| D. Orbital position is quantized. |
| Practice 4.1.4 |
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| A hydrogen atom is in its ground state. Incident on the atom are many photons each having energy of 10.5 eV. The result is which of the following? |
| A. The photons pass by the atom without interaction. |
| B. The atom is ionized. |
| C. The atom is excited to a higher allowed state. |
A hydrogen atom initially in its ground state absorbs a photon, which excites the atom to the n = 3 level. Determine the wavelength and frequency of the photon.
The n = 3 state of hydrogen has E3 = -1.51 eV.
(a) Why is the energy negative?
(b) What is the physical significance of the specific number 1.51 eV?
Why is there no stationary state of hydrogen with E = -9 eV?
Draw and label an energy level diagram for hydrogen. On it, show all the transitions by which an electron in the n = 4 state could emit a photon.
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