Download Chapter 3

Guided Reading Section
1 (Unit 3)
(Chapter 3)
1. An atom is_______________________________________________________________
_______________________________________________________________________________________________
2. Which Greek thinker, as early as 400 B.C., supported the particle theory of matter?
__________________________________________
3. Where did the name atom originate?__________________________________________
_______________________________________________________________________________________________
Foundations of Atomic Theory
4. Finish these sentences:
a. An element is a substance________________________________________________
_____________________________________________________________________.
b. Elements combine to form________________________________________________
_____________________________________________________________________________________________
_______________________________________________.
c. The transformation of a substance__________________________________________
_____________________________________________________________________________________________
_______________________________________________.
5. State the law of the conservation of mass.______________________________________
________________________________________________________________________________________________
________________________________________________
Dalton's Atomic Theory
6. In 1808, an English schoolteacher named _________________________________ proposed an explanation for the law
of the conservation of mass.
7. Finish these statements that sum up his theory.
a. All matter is composed of extremely small particles called ________________.
b. Atoms of a given element are identical in __________________________________
______________________; atoms of different elements ____________ in size, mass, and other properties.
c. Atoms cannot be ______________________________________________________.
d. Atoms of different elements combine in simple _______________________________ to form
______________________________________.
e. In chemical reactions, atoms are__________________________________________
_____________________________.
Modern Atomic Theory
8. Which aspects of Dalton's theory have been proven incorrect?
a.___________________________________________________________________
b.___________________________________________________________________________________________
_____________________________________________
9. What two important concepts remain unchanged?
a.____________________________________________________________________
b.___________________________________________________________________________________________
10. All atoms consist of _____________________________________.
11. The ____________________ is a very small region located at the _______________ of the atom.
12. The nucleus is made up of at least one positively charged particle called a ____________________ and usually one or
more neutral particles called ______________________.
13. Surrounding the nucleus is a region occupied by negatively charged particles called ___________________________.
14. Protons, neutrons, and electrons are often referred to as _____________________________________.
Discovery of the Electron
15. What did investigators notice when current was passed through a cathode-ray tube?_______________
__________________________________________________________________________________
16. What two hypotheses did these investigators propose?
a._________________________________________________________________________________
b._________________________________________________________________________________
17. What did the English physicist J. J. Thomson conclude?______________________________________
___________________________________________________________________________________
___________________________________________________________________________________
18. Cathode rays have _____________________ properties regardless of the element used to produce
them. Therefore, it was concluded that ____________________ are present in atoms of all elements.
19. Which American physicist measured the charge of the electron? ______________________________
20. Based on what was learned about electrons, what two inferences were made about atomic structure?
a.__________________________________________________________________________________
__________________________________________________________________________________
b.__________________________________________________________________________________
_______________________________________________________________________________
21. What was the name of the model that Thomson proposed? ___________________________________
Discovery of the Atomic Nucleus
22. What did Ernest Rutherford expect to happen when he bombarded a thin piece of gold foil with alpha
particles?__________________________________________________________________________
23. What happened instead? ______________________________________________________________
24. How did Rutherford describe this?_______________________________________________________
___________________________________________________________________________________
25. What conclusions did Rutherford come to?
a.______________________________________________________________________________________________
____________________________________________________________________
b.______________________________________________________________________________________________
_____________________________________________________________________
c.______________________________________________________________________________________________
_____________________________________________________________________
26. What did Rutherford call the positive bundle of matter at the center of the atom? __________________
27. If the nucleus were the size of a marble, how would it compare to the size of the atom?
___________________________________________________________________________________
28. Which of Rutherford's students proposed a model showing the positions of the electrons? ________________________
Composition of the Atomic Nucleus
29. Except for the simplest hydrogen atom, all atomic nuclei contain _______________ and __________________.
30. A proton has a positive charge _______________ in magnitude to the negative charge of an electron.
21. Atoms are electrically _____________________ because they contain equal numbers of protons and electrons.
32. Which particle determines the identity of an atom? _____________________
33. What do we call the forces that hold together the protons and neutrons in a nucleus? ___________________
34. Fill in the following table.
Properties of Subatomic Particles
Particle
Electron
Proton
Neutron
Symbols
Relative Charge
Mass Number
Relative Mass (amu)
Actual Mass (kg)
Atomic Number
35. Define atomic number:_________________________________________________________
36. Which number identifies an element? _____________________________________________
37. How do we know that a silver atom has 47 electrons?_______________________________________________
Isotopes
38. What are the names of the three hydrogen isotopes, and how many neutrons does each have?
a._________________________________________________
b._________________________________________________
c._________________________________________________
39. Define isotope:_______________________________________________________________
___________________________________________________________________________
40. Isotopes of a particular element have the same number of _____________________ and ____________________, but
different numbers of ________________________.
Mass Number
41. What information is needed to identify an isotope?____________________________________
___________________________________________________________________________
42. Define mass number:___________________________________________________________
___________________________________________________________________________
Designating Isotopes
43. What are the two methods for designating an isotope?
a.______________________________________________________________________
b.______________________________________________________________________
44. Give an example of each method using the uranium isotope used as fuel for nuclear power.
a. ________________________________________
b.________________________________________
45. In an isotope's nuclear symbol, what does the superscript (top number) indicate?
___________________________________________________________________________
46. In an isotope's nuclear symbol, what does the subscript (bottom number) indicate?
___________________________________________________________________________
47. How can we determine the number of neutrons?____________________________________
___________________________________________________________________________
Relative Atomic Masses
48. Why do scientists use a relative atomic mass rather than the actual atomic mass?
______________________________________________________________________________________________
________________________________________________________
49. Which isotope has been chosen as the standard?_____________________________________
50. What mass has arbitrarily been assigned to this isotope?______________________________
51. Define atomic mass unit:_______________________________________________________
___________________________________________________________________________
Average Atomic Masses of Elements
52. Most elements occur naturally as _________________ of isotopes.
53. Define average atomic mass:___________________________________________________
______________________________________________________________________________________________
54. What two factors does the average atomic mass depend on?
a. _______________________________________________
b._________________________________________________________________________
55. How do we calculate average atomic mass?________________________________________
________________________________________________________________________________________
Electrons as Waves
56. Which scientist hypothesized that electrons have wave-like properties? ________________________
The Heisenberg Uncertainty Principle
57. State the Heisenberg uncertainty principle:_______________________________________________
______________________________________________________________________________________________
The Schrodinger Wave Equation
58. Which scientist used the hypothesis that electrons have a dual wave-particle nature to develop an equation that treated
electrons in atoms as waves? _________________________________________
59. Together with the Heisenberg uncertainty principle, the Schrodinger wave equation laid the foundation for
__________________________________________________________________.
60. What is quantum theory?______________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________
61. Define orbital:______________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________
Atomic Orbitals and Quantum Numbers
62. In the Bohr atomic model, electrons of increasing energy occupy _________________ farther and farther from the
nucleus.
63. How is Schrodinger's model different from Bohr's model?___________________________________
______________________________________________________________________________________________
______________________________________________________________________
64. What are quantum numbers?___________________________________________________________
__________________________________________________________________________________
Spin Quantum Number
65. The electron exists in one of two possible spin states, which creates a
_______________________________________________________.
66. A single orbital can hold a maximum of how many electrons? ___________________
67. These two electrons must have __________________________ spin states.