Unit 3: Atomic Theory, Subatomic Particles, and Quantum Mechanics
Name____________________________________ Date Started_____________
Dalton’s Atomic Theory
1. List the major points in Dalton’s atomic theory.
2. According to Dalton’s atomic theory, can more than one compound be made from atoms of the
same two elements?
3. What part of Dalton’s theory accounts for the Law of Conservation of Mass?
4. What part of Dalton’s theory accounts for the law of definite composition?
5. The brilliance with which magnesium burns makes it ideal for use in flares and flash bulbs.
Compare the mass of magnesium that burns with the mass of magnesium in the magnesium
oxide ash that forms. Explain this in terms of atomic theory.
6. The chemical name for limestone, a compound of calcium, carbon and oxygen, is calcium
carbonate. When heated, limestone decomposes into solid calcium oxide and gaseous carbon
dioxide. From the names of the products, tell where the atoms of each element may be found
after the reaction. How does the atomic theory explain this?
Subatomic Particles
7. Identify and explain the part of Dalton’s atomic theory that was first proved incorrect.
8. Compare the three major parts of an atom in charge and mass.
9. What did Thompson’s cathode ray experiments contribute to the discovery of the electron?
10. Compare and contrast protons and neutrons.
11. Compare and contrast electrons and protons.
12. Compare and contrast electrons and neutrons.
The Nuclear Atom
13. How can we account for the fact that most of the alpha particles in the Rutherford scattering
experiment passed directly through a solid sheet of gold?
14. How can we account for the fact that, in the Rutherford scattering experiment, some of the
alpha particles were deflected from their paths through the gold foil, and some were even
bounced back at various angles?
15. What major conclusions were drawn from the Rutherford scattering experiment?
16. What name is given to the central part of the atom?
17. Describe the activity of electrons according to the planetary model of the atom.
Isotopes
18. Compare the number of protons and electrons in an atom, the number of protons and neutrons,
and the number of electrons and neutrons.
19. Can two different elements have the same atomic number? Explain.
20. Carbon, as found in nature, consists of two isotopes. Most atoms have a mass number of 12,
but a few have a mass number of 13. For each isotope, indicate the (a) atomic number; (b)
number of protons; (c) number of neutrons; (d) mass number; (e) nuclear charge.
21. Explain why isotopes of different elements can have the same mass number but isotopes of the
same element cannot.
Electromagnetic Spectrum
22. What is electromagnetic radiation?
23. The visible spectrum is a small part of the whole electromagnetic spectrum. Name several other
parts of the whole spectrum that are included in our everyday vocabulary.
24. What do visible light and radio waves have in common?
25. Identify measurable properties that are used in describing light.
26. Calculate the frequency of visible red light that has a wavelength of 6.85x10-7 m.
27. What is the frequency of ultraviolet light with a wavelength of 2.18x10-7 m?
28. Television waves have a wavelength of about one meter. What is the frequency of television
signals?
29. Gamma rays are used to sterilize containers of medical supplies, and their wavelength is
typically about 10-11 m. What is the corresponding frequency?
30. Calculate the wavelength, in m, of the radio waves sent out by an AM station broadcasting at
1.43x106 Hz.
31. What is the wavelength, in m, of the radio waves sent out by an AM radio station that
broadcasts at 5.3x105 Hz?
32. FM radio stations broadcast at frequencies typically expressed in MHz, where M is the prefix for
mega, 106. What is the wavelength, in m, of the electromagnetic radiation emitted by a station
broadcasting at 92.3 MHz? (=9.2x107 Hz)
33. A radio disc jockey identifies a radio station as “Rock 100, 100.5 of the FM dial.” (See Question
11.) What is the wavelength of the radiation emitted by this station’s transmitter (in m)?
(1.00x108 Hz)
The Quantization of Light
34. Which of the following are quantized? (a) milk from a cow; (b) milk from a store; (c) wheels in
an automobile factory; (d) temperature; (e) amount of rainfall.
35. Which of the following are not quantized? (a) shoelaces; (b) cars passing through a toll plaza in a
day; (c) birds in an aviary; (d) flow of a river in m3/hr; (e) percentage of salt in a solution.
The Bohr Model of the Atom
36. Electron energies are quantized within the atoms. What is the meaning of t his statement?
37. What kind of light would be emitted by atoms if the electron energy were not quantized?
Explain.
38. What must happen to an atom before it can emit light?
39. What is meant when an atom is “in its ground state”?
40. Which atom is more likely to emit light, one in the ground state or one in an excited state?
Why?
41. Identify the shortcomings of the Bohr Theory of the atom.
42. Identify the major advances that came from the Bohr model of the atom.
Questions 22-23: Complete the information in the tables.
43.
Name of
Element
Nuclear
Symbol
Atomic
number
Mass
number
4
Protons
Neutrons
52
24
33
47
207
Electrons
60
125
27
44.
Name of
Element
Nuclear
Symbol
Atomic
number
Mass
number
Protons
Neutrons
Electrons
24
21
122
Antimony
122
72
37
11
17
12
Atomic Mass
45. What is an atomic mass unit?
46. What advantage does atomic mass unit have over grams when speaking of the mass of an atom
or a subatomic particle?
47. The mass of an average atom of a certain element is 6.66 times as great as the mass of an atom
of carbon- 12. Using the periodic table, identify the element.
48. Lithium exists in two natural isotopes. The atomic mass of one is 6.10512 amu and the other is
7.01600 amu. Why isn’t the atomic mass of lithium of the periodic table 6.51556, the average of
these two numbers?
49. The atomic masses of the natural isotopes of neon are 19.99244 amu, 20.99395 amu, and
21.99138 amu. The average of these three masses is 20.99259 amu. Which isotope do you
expect is the most abundant in nature? Explain.
Questions 29-33: Percentage abundances and atomic masses (amu) of the natural isotopes of an
element are given. (a) Calculate the atomic mass of each element from these data (show your work). (b)
Using the periodic table, identify the element.
Percent (%) abundance
Atomic Mass (amu)
50. 69.09
30.91
62.929
64.9278
51. 51.82
48.18
106.9041
108.9047
52. 37.07
62.93
184.9530
186.9560
53. 57.25
42.75
120.9038
122.9041
54. 0.193
0.250
88.48
11.07
135.907
137.9057
139.9053
141.9090