Download AP Chemistry Chapter 7 Review Packet

AP Chemistry Chapter 7 Review Packet
Name________________________________
35.
What is the minimum wavelength of a photon of light that can excite an electron in the
hydrogen atom from the n = 1 to the n = 8 energy level?
36.
In the hydrogen spectrum, what is the wavelength of light associated with the n = 2
to n = 1 electron transition?
ΔE =  2.178 x 1018 J (1/nf2  1/ni2)
ΔE =  2.178 x 1018 J (1/12  1/22)
ΔE =  2.178 x 1018 J (1/1  1/4)
ΔE =  2.178 x 1018 J (1  0.25)
ΔE =  2.178 x 1018 J (0.75)
ΔE =  1.63 x 1018 J
E = hν and c = λν so E = hc/λ and λ = hc/E
λ = (6.626 x 1034 J∙s) (2.9979 x 108 m/s)
1.63 x 1018 J
λ = 1.22 x 107 m
37.
What is the energy of a photon of blue light that has a wavelength of 450 nm?
1m
450 nm = 4.50 x 107 m
9
10 nm
ΔE = hc/λ
ΔE = (6.626 x 1034 J∙s) (2.9979 x 108 m/s)
4.50 x 107 m
ΔE = 4.4 x 1019 J
38.
The bright yellow light emitted by a sodium vapor lamp consists of two emission lines at
589.0 nm and 589.6 nm. What are the frequency and the energy of a photon of light at
each of these wavelengths? What are the energies in kJ/mol?
For 589.0 nm:
1m
109 nm
589.0 nm = 5.890 x 107 m
For 589.6 nm:
1m
109 nm
589.6 nm = 5.896 x 107 m
ν = c/λ
ν = (2.9979 x 108 m/s)/(5.890 x 107 m)
ν = 5.090 x 1014 Hz
ν = c/λ
ν = (2.9979 x 108 m/s)/(5.896 x 107 m)
ν = 5.085 x 1014 Hz
ΔE = hν
ΔE = (6.626 x 1034 J∙s)(5.090 x 1014 Hz)
ΔE = 3.373 x 1019 J
ΔE = hν
ΔE = (6.626 x 1034 J∙s)(5.0850 x 1014 Hz)
ΔE = 3.369 x 1019 J
1 kJ 3.373 x 1019 J 6.022 x 1023 photons =
103 J
1 photon
1 mole
1 kJ 3.369 x 1019 J 6.022 x 1023 photons =
103 J
1 photon
1 mole
= 203.1 kJ/mol
= 202.9 kJ/mol
39.
The orange-yellow color of sodium-vapor streetlights results from electrons in sodium
atoms falling from 3p to 3s orbitals. The wavelength of one orange-yellow line in the
spectrum of sodium is 589 nm.
a. Write the electron configuration for the ground state of sodium.
b. Write the electron configuration of the excited state of the sodium atom that is
involved in this change in energy level.
c. Calculate the number of unpaired electrons in the excited state of sodium.
Draw a diagram to illustrate the paired and unpaired electrons.
d. Write every set of quantum numbers associated with the electrons in the
ground state of sodium.
e. Calculate the difference in energy between the 3 p and 3 s orbitals of the
sodium atom.
40.
Hint: When electrons fall from an excited state to the ground state, E is going to be
negative because energy is released in the form of light. Be sure to include the negative
sign on the energy value when using Bohr's energy level formula if the electron is falling
from an excited state to a lower energy state.
From the information below, identify element X.
a. The wavelength of the radio waves sent by an FM station broadcasting at 81.9 MHz is
30 million times greater than the wavelength corresponding to the energy difference
between a particular excited state of the hydrogen atom and the ground state.
b. Let V represent the principal quantum number for the valence shell of element X. If an
electron in the hydrogen atom falls from shell V to the inner shell corresponding to the excited
state mentioned in part a, the wavelength of light emitted is the same as the wavelength of an
electron moving at a speed of 1.67 x 103 m/s.
c. The number of unpaired electrons for element X is the same as the maximum number of
electrons in an atom that can have the quantum number classifications,
n = 4, ℓ = 1, ms =   .
d. Let A equal the charge of the stable ion that would form when the undiscovered
element 119 forms ionic compounds. This value of A also represents the angular
momentum quantum number for the subshell containing the unpaired electrons for
element X.