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Complete these 15 questions by the end of the term. Unlike your
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enter the numeric value accurate to three signi!cant !gures.
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Module 9 – CH 10 and 11 HW – PHYS 102 January 2020 Online, section Wicker (0005), Spring 2020 | WebAssign 3/7/20, 11:09 PM
Things around you are emitting infrared radiation that includes the wavelength 1.03 10 m. What is the energy of these IR
photons?
eV
Gamma rays (γ-rays) are high-energy photons. In a certain nuclear reaction, a γ-ray of energy 0.779 MeV (million electronvolts) is
produced. Compute the frequency of such a photon.
Hz
In a typical electron microscope, the momentum of each electron is about 1.3 10 kg-m/s. What is the de Broglie wavelength of
the electrons?
m
If a proton were traveling the same speed as electrons in a TV picture tube (about 7.0 10 m/s), what would its de Broglie
wavelength be? The mass of a proton is 1.67 10 kg.
m
-5
-22
7
-27
Module 9 – CH 10 and 11 HW – PHYS 102 January 2020 Online, section Wicker (0005), Spring 2020 | WebAssign 3/7/20, 11:09 PM
(a) A hydrogen atom has its electron in the level. The radius of the electron’s orbit in the Bohr model is 1.905 nm. Find the de
Broglie wavelength of the electron under these circumstances.
m
(b) What is the momentum, mv, of the electron in its orbit?
kg-m/s
A hydrogen atom has its electron in the state.
(a) How much energy would have to be absorbed by the atom for it to become ionized from this level?
eV
(b) What is the frequency of the photon that could produce this result?
Hz
A hydrogen atom initially in the n = 2 level emits a photon and ends up in the ground state.
(a) What is the energy of the emitted photon?
eV
(b) If this atom then absorbs a second photon and returns to the n = 2 state, what must the energy of this photon be?
eV
n = 6
n = 3
Module 9 – CH 10 and 11 HW – PHYS 102 January 2020 Online, section Wicker (0005), Spring 2020 | WebAssign 3/7/20, 11:09 PM
A neutral aluminum atom is in its ground state electronic configuration. How many of its electrons are in the n = 3 level?
electrons
The n = 1 level contains 8 electrons, the n = 2 level contains 2 electrons, and the n = 3 level contains 4 electrons.
The n = 1 level contains 2 electrons, the n = 2 level contains 8 electrons, and the n = 3 level contains 3 electrons.
The n = 1 level contains 1 electron, the n = 2 level contains 6 electrons, and the n = 3 level contains 6 electrons.
The n = 1 level contains 1 electron, the n = 2 level contains 8 electrons, and the n = 3 level contains 4 electrons.
The n = 1 level contains 2 electrons, the n = 2 level contains 8 electrons, and the n = 3 level contains 5 electrons.
Determine the nuclear composition (number of protons and neutrons) of the following isotopes.
(a) iron-56
protons
neutrons
(b) nickel-58
protons
neutrons
(c) antimony-121
protons
neutrons
(d) erbium-166
protons
neutrons
(e) uranium-238
protons
neutrons
(Z = 13)
Module 9 – CH 10 and 11 HW – PHYS 102 January 2020 Online, section Wicker (0005), Spring 2020 | WebAssign 3/7/20, 11:09 PM
The isotope lithium-8 undergoes beta decay. Write the reaction equation and determine the identity of the daughter nucleus.
The isotope astatine-201 undergoes alpha decay. Write the reaction equation and determine the identity of the daughter nucleus.
Li → Be + e
8
3
9
4
−1
Li → Be + e
8
3
8
4
−1
Li → He + e
8
3
7
2
−1
Li → Be + e
8
3
7
4
−1
Li → He + e
8
3
8
2
−1
At → Fr + He 201
85
197
87
4
2
At → Bi + He 201
85
197
83
4
2
At → Bi + He 201
85
199
83
4
2
At → Fr + He 201
85
205
87
4
2
At → Bi + He 201
85
205
83
4
2
Module 9 – CH 10 and 11 HW – PHYS 102 January 2020 Online, section Wicker (0005), Spring 2020 | WebAssign 3/7/20, 11:09 PM
The isotope palladium-120* undergoes gamma decay. Write the reaction equation, and determine the identity of the daughter
nucleus.
A Geiger counter registers a count rate of 5,200 counts per minute from a sample of a radioisotope. Six minutes later, the count rate
is 1,300 counts per minute. What is the half-life of the radioisotope?
min
An accident in a laboratory results in a room being contaminated by a radioisotope with a half-life of 4 days. If the radiation is
measured to be eight times the maximum permissible level, how much time must elapse before the room is safe to enter?
days
Pd* → Rh + γ
120
46
120
45
Pd* → Pd + γ
120
46
120
46
Pd* → Ag + γ
120
46
120
47
Pd* → Pd + γ
120
46
121
46
Pd* → Ag + γ
120
46
121
47