Quantum Mechanics and
Atomic Theory
Chapter 12
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Quantum – ch 12
1. A photon has a frequency (v) of 5.45 x 108 MHz
a. Calculate the photons wavelength (λ) in nm
b. What type of light is the photon?
c. Calculate the energy (in J) of one photon and for one mole of
photons (kJ/mol)
Quantum – ch 12
2. Determine the following:
a. Higher frequency:
b. Higher Energy:
c. Longer wavelength:
IR
or
X-Rays or
yellow or
UV
Microwaves
purple
Quantum – ch 12
3. Consider the following transitions. Which will emit light with a
longer wavelength?
a. n = 4  n = 2
or
n=3  n=2
b. n = 3  n = 1
or
n=1  n=3
c. n = 5  n = 3
or
n=3  n=1
Quantum – ch 12
4. Calculate the wavelengths (nm) emitted for the following electronic
transitions in a hydrogen atom.
a. n = 5  n = 3
b. n = 3  n = 1
c. How would your answers vary if the electronic transitions were
for Ne9+?
Quantum – ch 12
5. An excited hydrogen atom with an electron in n = 5 state emits light
having a frequency of 6.9 x 1014 s-1. Determine the principal
quantum level (n) for the final state in this electronic transition.
Quantum – ch 12
6. The figure below represents part of the emission spectrum for a oneelectron ion in the gas phase. All of the lines result from electronic
transitions from excited states to the n = 3 state.
A
B
Wavelength
a. What electronic transitions correspond to lines A and B?
b. If the wavelength of line B is 142.5 nm, calculate the
wavelength of line A.
Quantum – ch 12
7. An electron is excited from the ground state to the n = 3 state in a
hydrogen atom. Which of the following statements are true?
a. It takes more energy to ionize the electron from n= 3 than from
the ground state.
b. The electron is farther form the nucleus on average in the n = 3
state than in the ground state
c. The wavelength of light emitted if the electron drops from n = 3
to n = 2 is shorter than the wavelength of light emitted if the
electron falls from n = 3 to n = 1.
d. The wavelength of light emitted when the electron returns to the
ground state from n = 3 is the same as the wavelength
absorbed to go from n = 1 to n = 3.
Quantum – ch 12
8. Calculate the energy (in kJ/mol) required to remove the electron in
the ground state for each of the following one-electron species.
a. H
b. Fe25+
c. Account for the differences
Quantum – ch 12
9. The ionization energy of gold is 891 kJ/mol. Calculate the
maximum wavelength (nm) of light require to remove an electron.
Quantum – ch 12
10. It takes 208.4 kJ of energy to remove 1 mol of electrons from the
atoms on the surface of rubidium metal. If rubidium metal is
irradiated with 254-nm light, what is the maximum kinetic energy
the released electrons can have?
Quantum – ch 12
11. Calculate the wavelength of an electron (9.11 x 10-31 kg) traveling
at 5 x 107 m/s.
Quantum – ch 12
12. Which of the following sets of quantum numbers are unacceptable?
Explain your answers.
a. (1, 0, 1/2, -1/2)
b. (3, 0, 0, 1/2)
c. (2, 2, 1, 1/2)
d. (3, 2, 1, 1)
e. (4, 3, -2, 1/2)
Quantum – ch 12
Quantum Numbers
1. n ⇒ principal quantum number ⇒ proportional to the size and
energy of the orbital ⇒ range is 1 to ∞
2. l ⇒ angular momentum quantum number ⇒ shape of the subshell ⇒
range is 0 to ∞
3. ml ⇒ magnetic quantum number ⇒ orbital orientation ⇒
range is –l to +l
4. ms ⇒ electron spin quantum number ⇒ +1/2 or -1/2
Quantum – ch 12
Quantum – ch 12
l=0 ⇒ s
l=1 ⇒ p
l=2 ⇒ d
l=3 ⇒ f
Quantum – ch 12
13. How many electrons in any one atom can have the following
quantum numbers?
a. n = 5
b. n = 6, l = 0
c. n = 4, l = 2
d. n = 4, l = 3, ml = -2
e. n = 2, l = 0, ml = 0, ms = -1/2
Quantum – ch 12
14. Fill in the following table:
Element
Cl
Ni
Cr
Ag
Te2–
Fe2+
Ground State Electron
Configuration
Number of Valence
Electrons
Number of Unpaired
Electrons
Quantum – ch 12
Aufbau principle ⇒ electrons will fill from low to high energy
Hund’s Rule ⇒ When filling degenerate orbitals don’t pair up until each orbital has 1 e–
Quantum – ch 12
Electron
Configuration ⇒
Order of filling is
left to right and top to
bottom on the
periodic table
Quantum – ch 12
15. Determine if each of the following corresponds with an excited
state or ground state electron configuration.
a. [Ar]4s24p5
b. [Kr]6s1
c. [Ne]3s23p4
Quantum – ch 12
16. Which of the following has the largest radius?
a. Al or Si
b. F or Cl
c. S or S2d. K or K+
Quantum – ch 12
17. Which of the following has the greatest ionization energy?
a. K or Ca
b. P or As
c. Sr or Sr2+
Quantum – ch 12
18. Which of the following has the most negative electron affinity?
a. Br or Kr
b. C or Si
Quantum – ch 12
19. The successive ionization energies for an unknown element are:
I1 = 896 kJ/mol
I2 = 1752 kJ/mol
I3 = 14,807 kJ/mol
I4 = 17,948 kJ/mol
Which family does the unknown element most likely belong?