Download Chapter 7 Worksheet November 1

Chem 31 SI 11/01/09
Chapter 7 Worksheet
Chapter 7 Worksheet
1. A) Draw a basic sine wave
B) Superimpose a second wave with the same wavelength but stronger amplitude
C) Superimpose a third wave with the same amplitude as the first but with a shorter wavelength
2. The size of the amplitude corresponds to:
A. The number of wave cycles per second
B. The intensity of the electromagnetic radiation (brightness)
C. The amount of energy contained in an electromagnetic wave
D. The speed of light
3. (#40 from the text) Place the following types of radiation in order of increasing wavelength and increasing energy per
photon:
Gamma Rays // Radio Waves // Microwaves // Visible Light
4. If an X-ray machine emits E.M.R with a wavelength of 1.00 x 10 -10 meters, what is the frequency?
Answer = 3.00 x 1018 Hz
5. A police officer uses a radar gun to catch Heisenberg speeding. The gun operates at a frequency of 22.235 x 10 9 Hz. Find
the wavelength in nanometers of this radiation. (Bonus: What did Heisenberg say to the police officer when the police
officer asked if he knew how fast he was going?)
Answer = 1.3483 x 107 nm
6. Describe the two types of interference:
1)
2)
Chem 31 SI 11/01/09
Chapter 7 Worksheet
7. During constructive interference:
A. The amplitudes are summed together
B. The wavelengths are summed together
C. The light waves bend around an object
D. The light waves disperse into their component colors
8. What might the problem be if our retina could detect low frequency electromagnetic radiation?
9. What does it mean to be quantized vs. continuous?
10. (for Practice 7.2 – page 290) If a 100 watt light bulb radiates energy at a rate of 100 J/sec, and all of the light emitted
has a wavelength of 525 nm, how many photons are emitted per second?
Answer: 2.64 x 1020 photons
11. What 2 experiments lead to the theory that light does in fact have particle like behavior?
12. Why does the Bohr model of the Hydrogen atom defy classical physics?
13. True or False: The term “orbital” in the quantum mechanical model of the atom is essentially the same thing as “orbits”
in the Bohr model of the atom.
14. (#27-29 from text) What are the possible values of n, l, and ml? What does each of these determine?
Chem 31 SI 11/01/09
Chapter 7 Worksheet
15. (#67d from text) Calculate the wavelength of the light emitted when an electron in a hydrogen atom makes the
transition from n = 5 to n = 2 and indicate the region of the electromagnetic spectrum where the light is found:
Answer = 4.34 x 10-7 m or 434 nm. = Visible Light (Blueish)
16. (#70 from text) An electron in a hydrogen atom relaxes to the n = 4 level, emitting light of 114 THz. What is the value
of n for the level in which the electron originated?
Answer: n = 6
17 (BONUS) You are at a baseball game and a person sitting next to you is trying to impress their date by telling them that
the baseball has vibrations, and that its position in space cannot totally be determined by the batter. You know that such
concepts only really apply to infinitesimally small particles such as the electron. Using the deBroglie relationship and the
Heisenberg uncertainty principle, compare an electron in motion vs. a baseball in motion to mathematically prove your
point (assume the mass of the baseball is 143g and it travels at 95 mph , the mass of an electron is 2.74 x 10-31 kg, assume
an electron is traveling at a speed of 2.65 m/s).
18. Which of the following accurately describes l (the angular momentum quantum number)?
A. The value of l can be both positive and negative
B. The value of l specifies the orientation of the orbital
C. The value of l specifies the energy level of the orbital.
D. The number of possible l values equals the value of n.
Chem 31 SI 11/01/09
Chapter 7 Worksheet
19. List all of the possible values of l (angular momentum) and m (magnetic) quantum numbers for the following values of
n (the principal quantum number):
A) n = 1
B) n = 2
C) n = 3
D) n = 4
20. Based on the above question, the total number of orbitals possible for a given n-value is equal to:
A. n
B. n2
C. n-1
D. 2n + 1
21. Supply the missing quantum numbers and sublevel names:
n
l
ml
Name
__
__
0
4p
2
1
0
__
3
2
-2
__
__
__
__
2s
22. Indicate why the following sets of quantum numbers are wrong:
A) n =1 , l = 1 , m = 0 , Name = 1p
B) n = 4 , l = 3 , m = +3 , name = 4d
C) n = 3 , l = 1 , m = -2 , Name = 3p
D) Name = 2d
Chem 31 SI 11/01/09
Chapter 7 Worksheet
23. (# 78 from text) The energy required to ionize sodium is 496 kJ / mol. What minimum frequency
of light is required to ionize sodium?
Answer = 1.24 x 1015 Hz
24. (#83 from text) The binding energy of electrons in a metal is 193 kJ / mol. Find the threshold
frequency of the metal.
Answer = 4.84 x 1014 Hz
Chem 31 SI 11/01/09
Chapter 7 Worksheet
Chapter 7 Useful Information
c=λ ∙ ν
c = 2.99792458 x 108 meters/second = the speed of light = the speed of any EM wave in a vacuum
λ = wavelength
ν = frequency (measured in Hz or cycles per second)
λ ultraviolet light = 1 x 10-8 meters
λ infrared light = 1 x 10-4 meters
h = 6.626 x 10-34 Joules ∙ Second = Plancks constant
∆Eatom = E emitted (or absorbed) radiation = hν = Ephoton = hc/λ
DeBroglie relationship between wavelength (λ), mass (m), and velocity (v) of a particle:
λ = h/mv
φ = energy of a photon when threshold is achieved
hv = φ
Calculating the difference between two energy levels in the H atom:
∆E = Efinal – Einitial = hc/λ = -2.18 x 10-18 J
Heisenberg Equation:
∆x + m∆v ≥ h/4π
Visible spectrum = 400 – 750nm