Conceptual Questions

ssm Solution is in the Student Solutions Manual.

| 1 | At room temperature, most of the atoms of atomic hydrogen contain electrons that are in the ground state or n = 1 energy level. A tube is filled with atomic hydrogen. Electromagnetic radiation with a continuous spectrum of wavelengths, including those in the Lyman, Balmer, and Paschen series, enters one end of this tube and leaves the other end. The exiting radiation is found to contain absorption lines. To which one (or more) of the series do the wavelengths of these absorption lines correspond? Assume that once an electron absorbs a photon and jumps to a higher energy level, it does not absorb yet another photon and jump to an even higher energy level. Explain your answer.

| 2 | Refer to Question 1. Suppose the electrons in the atoms are mostly in excited states. Do you expect there to be a greater or lesser number of absorption lines in the exiting radiation, compared to the situation when the electrons are in the ground state? Account for your answer.

| 3 | ssm When the outermost electron in an atom is in an excited state, the atom is more easily ionized than when the outermost electron is in the ground state. Why?

| 4 | In the Bohr model for the hydrogen atom, the closer the electron is to the nucleus, the smaller is the total energy of the atom. Is this also true in the quantum mechanical picture of the hydrogen atom? Justify your answer.

| 5 | Conceptual Example 6 provides background for this question. Consider two different hydrogen atoms. The electron in each atom is in an excited state. Is it possible for the electrons to have different energies but the same orbital angular momentum L, according to (a) the Bohr model and (b) quantum mechanics? In each case, give a reason for your answer.

| 6 | In the quantum mechanical picture of the hydrogen atom, the orbital angular momentum of the electron may be zero in any of the possible energy states. For which energy state must the orbital angular momentum be zero? Give your reasoning.

| 7 | Can a 5g subshell contain (a) 22 electrons and (b) 17 electrons? Why?

| 8 | ssm An electronic configuration for manganese (Z = 25) is written as 1s2 2s2 2p6 3s2 3p6 4s2 3d4 4p1. Does this configuration of the electrons represent the ground state or an excited state? Consult Figure 30-17 for the order in which the subshells fill, and account for your answer.

| 9 | The drawing shows the X-ray spectra produced by an X-ray tube when the tube is operated at two different potential differences. Explain why the characteristic lines occur at the same wavelengths in the two spectra, whereas the cutoff wavelength shifts to the right when a lower voltage is used to operate the tube.

| 10 | ssm In the production of X-rays, it is possible to create Bremsstrahlung X-rays without producing the characteristic X-rays. Explain how this can be accomplished by adjusting the electric potential difference used to operate the X-ray tube.

| 11 | The short wavelength side of X-ray spectra ends abruptly at a cutoff wavelength (see Figure 30-20). Does this cutoff wavelength depend on the target material used in the X-ray tube? Give your reasoning.

| 12 | Explain why a laser beam focused to a small spot can cut through a piece of metal.

| 13 | Suppose that a laser produces green light instead of the red light produced by a helium/neon laser. Are the photons emitted by this laser more energetic, less energetic, or of equal energy as compared to those emitted by the helium/neon laser? Justify your answer.

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