1. Chemistry Midterm Review

2. Question One
Describe the atomic model for each scientist listed. Be sure to mention information about the experiment and the location of the subatomic particles.
Dalton
Thomson
Rutherford
Bohr
Modern View
Answer

3. Answer 1 Dalton – indivisible, solid sphere (no subatomic particles)
Thomson- “plum pudding model” electrons are evenly distributed throughout a mass of protons. Model based on his cathode ray experiment
Rutherford- discovered mostly empty space surrounding a dense positively charged nucleus using through the gold foil experiment
Bohr- believed in a small positively charged nucleus containing the protons and neutrons surrounded by electrons in ORBITS of specific energy levels
Modern View- Also called the wave- mechanical model and the quantum model similar to Bohr but electrons are in regions of high probability based on energy level, and orbital.

4. Question 2
Compare the charge, size, and location of a proton, neutron, and electron.
Answer 2

5. Answer 2 Type of subatomic particle Size in amu Charge
Location in an atom
Proton 1 +1
nucleus
Neutron
Electron
1/2000 -1
Electron clouds surrounding nucleus

6. Question 3
Explain why the following two elements are isotopes. State the number of protons, electrons, and neutrons each isotope possesses.

7. Answer 3
They are isotopes because each have a different # of neutrons but the same number of protons and electrons.
Sn has 50 p+, 50 e-, 71 n0
Sn has 50 p+, 50 e-, 69 n0

8. List the seven metalloids
Question 4
List the seven metalloids

9. Answer 4 B
Si,
Ge, As
Sb, Te At

10. Question 5
Why is the formation of a solution a physical change while the ability to react with a chemical considered a chemical change?

11. Answer 5
“reacting” indicates a change in the physical properties of an element resulting in a new compound.
Formation of a solution is a physical property because a new compound has not been formed. Evaporation of the water would leave the original compound behind. (ex. salt dissolving in water)

12. List Properties of a metal and a nonmetal.
Question 6
List Properties of a metal and a nonmetal.

13. Answer 6 Nonmetals Metals Brittle Dull Poor conductors
High electronegativities and IE
Metals
Form cations
Shiny
Malleable
Ductile
Good conductors
Low electronegativites and IE
Solids except Hg

14. Question 7
A solid substance was tested in the laboratory. The test results are listed below.
• dissolves in water • is an electrolyte • melts at a high temperature
A)Na B) NaCl C) Cl D) NH3

15. Answer 7
A)Na B) NaCl C) Cl D) NH3

16. What is the correct formula for Cobalt(III) bromide?
Question 8
What is the correct formula for Cobalt(III) bromide?

17. Answer 8
CoBr3

18. What form of matter cannot be decomposed?
Question 9
What form of matter cannot be decomposed?

19. Answer 9
Element

20. Question 10
What happens to a nonmetal ion when it becomes a negative ion?
Mention difference in # of electrons
Changes in radius

21. Answer 10
Gains electrons
Radius increases

22. Question 11
What is the name of the property that indicates an element’s desire to attract electrons and which element has the greatest attraction?

23. Answer 11
Electronegativity
Fluorine

24. Question 12 What are the terms used to identify a pure substance?
What are the terms used to identify a mixture?

25. Heterogeneous and Homogeneous
Answer 12
Element and compound
Heterogeneous and Homogeneous

26. Question 13
What is the difference between an excited state electron and a ground state electron?

27. Answer 13 Ground state electrons are in the lowest energy state
Excited state electrons have absorbed energy allowing them to jump to a higher energy level.

28. Question 14 Which substance can be decomposed by chemical change?
beryllium
boron
methanol
magnesium

29. Answer 14 Which substance can be decomposed by chemical change?
beryllium
boron
methanol
magnesium

30. Question 15 What is the name for each type of phase change?
Solid liquid
Liquid  gas
Gas  liquid
Liquid  solid
Solid  gas

31. Answer 15
Melting
Boiling or vaporization
Condensation
Freezing / solidification
Sublimation

32. Question 16
What is the volume of a liquid with a density of 1.5 g/ml and a mass of 78g?

33. Answer 16
V=m/D
78g/4.5g/mL
=52 mL

34. Question 17
When a bond is formed, energy is (released/absorbed)
When a bond is broken, energy is (released/absorbed)

35. When a bond is formed, energy is (released/absorbed)
Answer 17
When a bond is formed, energy is (released/absorbed)
When a bond is broken, energy is (released/absorbed)

36. Question 18
What is the mass number of an atom which contains 28 protons, 28 electrons and 34 neutrons? 28 56 62 90

37. Answer 18
What is the mass number of an atom which contains 28 protons, 28 electrons and 34 neutrons? 28 56 62 90

38. Question 19
What is the % composition by mass of carbon in carbon dioxide [gram-formula mass 44 grams/mole]?

39. Answer 19
27 % C

40. Why does calcium have similar chemical properties to barium?
Question 20
Why does calcium have similar chemical properties to barium?

41. Both are Group 2 elements
Answer 20
Both are Group 2 elements
Both have the same number of valence electrons

42. Question 21
Which of the following terms indicate a chemical property and which indicate a physical property?
Flatten
Conduct
Corrode
Drawn into a wire
React

43. Answer 21
Chemical
Corrode
react
Physical
Flatten
Drawn
Conduct

44. What is the charge on a I-127 nucleus?
Question 22
What is the charge on a I-127 nucleus?

45. Answer 22
+53

46. Name the type of element as it appears in the order below.
Question 23
Name the type of element as it appears in the order below.
Ge  K  Ar  Br

47. Answer 23
Ge  K  Ar  Br
Metalloid, metal,
noble gas, nonmetal

48. How many electrons are contained in an Cu2+ ion?
Question 24
How many electrons are contained in an Cu2+ ion?

49. Answer 24
27 electrons

50. Question 25
Which electron configuration represents the electrons of atom of sodium in the excited?
2-8-1
2-8-2
2-7-3
2-7-2

51. Answer 25

52. Question 26
If an element is shiny and a good conductor, what type of element is it?

53. Answer 26
Metal

54. Compare the number of subatomic particles that compose N-14 and F-19.
Question 27
Compare the number of subatomic particles that compose N-14 and F-19.

55. Answer 27 N-14 Protons 7 Electrons 7 Neutrons 7 F-19 Protons 9
F-19 has two protons, two more electrons, and three more protons than
N-14

56. Which of the following is a molecular formula? CH4 C3H6
Question 28
Which of the following is a molecular formula?
CH4
C3H6

57. Answer 28
C3H6

58. In what ratio, will a calcium ion combine with a phosphide ion?
Question 29
In what ratio, will a calcium ion combine with a phosphide ion?

59. Answer 29
Ca3P2
3:2

60. Question 30
Two atoms with an electronegativity difference of 0.4 form a bond that is
ionic, because electrons are shared
ionic, because electrons are transferred
covalent, because electrons are shared
covalent, because electrons are transferred

61. Answer 30
Two atoms with an electronegativity difference of 0.4 form a bond that is
ionic, because electrons are shared
ionic, because electrons are transferred
covalent, because electrons are shared
covalent, because electrons are transferred

62. Question 31
Describe the difference between a particle diagram of a solid, liquid, and gas.

63. Solid particles are packed tightly
Answer 31
Solid particles are packed tightly
Liquids are close but have some space for movement
Gases are far apart

64. Compare the atomic radius of Ca to Mg and Sr.
Question 32
Compare the atomic radius of Ca to Mg and Sr.

65. The atomic radius falls in the middle of Mg and Sr.
Answer 32
The atomic radius falls in the middle of Mg and Sr.

66. Question 33
State the trend for each of the following properties across a period.
Ionization Energy
Electronegativity
Atomic radius

67. IE and Electronegativity increases across the period
Answer 33
IE and Electronegativity increases across the period
Atomic Radius decreases

68. Question 34
State the trend for each of the following properties down a group.
Ionization Energy
Electronegativity
Atomic radius

69. IE and Electronegativity decreases across the period
Answer 34
IE and Electronegativity decreases across the period
Atomic Radius increases

70. Question 35
When the equation __C8H16 + __O2 → __CO2 + __H2O  is correctly balanced using the smallest whole number coefficient, the coefficient of O2 is 1 8 12

71. Answer 35
When the equation __C8H16 + __O2 → __CO2 + __H2O  is correctly balanced using the smallest whole number coefficient, the coefficient of O2 is 1 8 12

72. Question 36 Is this a endothermic or exothermic reaction? A 3 B 2 C
380 k 2 A
280 k 1

73. Question 36
What is the gram formula mass of Li2SO4?
54g
55g
110g
206g

74. Answer 36
What is the gram formula mass of Li2SO4?
54g
55g
110g
206g

75. Question 37 What is the total mass in grams of 0.75 mole of SO2? 16 g

76. Answer 37 What is the total mass in grams of 0.75 mole of SO2? 16 g

77. Calculate the number moles in 48 grams of CO.
Question 38
Calculate the number moles in 48 grams of CO.

78. Answer 38
1.7 moles

79. Question 39
Which electron-dot formula represents a polar molecule?

80. Answer 39

81. What is the relationship between Celsius and Kelvin?
Question 40
What is the relationship between Celsius and Kelvin?

82. Answer 40
Kelvin = Celsius temp + 273