Answer Key
Name ___________________
Unit 5 Test
Date _________
Multiple Choice: Choose the answer that completes the question or statement. (each 2 points)
1. __C__What sublevels are in the third energy level?
A. s
B. s and p
C. s, p, and d
D. s, p, d, and f
2. __B__Identify the element with this electron configuration: 1s22s22p63s23p64s23d5
A. Cr
B. Mn
C. Fe
D. Tc
3. __D__How many valence electrons for this electron configuration: 1s22s22p3?
A. 2
B. 3
C. 4
D. 5
4. __B__What type of bond is present in calcium sulfate?
A. Potential Bond Energy
B. Ionic Bond
C. Covalent Bond
D. Electric Bond
5. __C__How do you write the formula for sulfur dioxide?
A. SO
B. S2O
C. SO2
D. S2O2
6. __A__When two atoms of chlorine bond together they share electrons in a covalent bond. How many
electrons does each chlorine atom share?
A. 1
B. 2
C. 3
D. 4
7. __B__In question number 6 above, how many valence electrons are in each bonded chlorine atom?
A. 6
B. 7
C. 8
D. 9
8. __C__The potential energy ____________ when stability increases because an element has bonded?
A. remains the same
B. increases
C. decreases
D. doubles
9. __B__Which of the following reactions decreases in potential energy and is exothermic?
A. H2O (s) → H2O (l)
B. Fe (s) + S (s) → FeS (s)
C. 2NH3 (g) → N2 (g) + 3H2 (g)
D. NaCl (s) → Na+ (aq) + Cl- (aq)
10. __C__Which of the following describes the process of aluminum phosphide decomposing into
aluminum and phosphorus?
A. ΔH is negative because bonds are formed
B. Exothermic
C. Endothermic- ΔH is positive
D. Dissociation of aluminum and phosphide
11. __B__What is the molar mass of calcium chloride?
A. 75 g/mol
B. 110 g/mol
C. 145 g/mol
D. 155 g/mol
12. __C__Calculate the number of grams in 5.09 moles of MgCl2. Round the answer to the correct
number of significant figures.
A. 0.05 grams
B. 0.0535 grams
C. 484 grams
D. 500 grams
13. __C__How many molecules are in 43.2 grams of dihydrogen monosulfide? Round the answer to the
correct number of significant figures.
A. 7.65 molecules
B. 7 x 1023 molecules
C. 7.65 x 1023 molecules
D. 8 x 1023 molecules
14. __C__Is matter conserved in the following reaction? NaOH(aq) + HCl(aq) → NaCl(s) + H2O(l)
A. No, the molar coefficients are not equal on both sides of the equation
B. No, the atoms are not balanced on both sides of the equation
C. Yes, the atoms are balanced on both sides of the equation
D. Yes, the molar coefficients add up to ten
15. __D__What are the molar coefficients that balance the following equation? __N2 + __H2 → __NH3
A. 1, 2, 3
B. 3, 2, 1
C. 2, 2, 2
D. 1, 3, 2
16. __B__Which of the following chemicals is a non-electrolyte?
A. Salt (NaCl)
B. Sugar
C. Potassium chloride
D. Barium nitrate
17. __B__When a diatomic gas (such as O2) dissolves in water it can make the water appear cloudy.
Would oxygen dissolved in water conduct electricity?
A. Yes, oxygen is a non-electrolyte
B. No, oxygen is a non-electrolyte
C. Yes, oxygen is an electrolyte
D. No, oxygen is an electrolyte
18. __A__Calcium chloride exhibits these properties: hard, brittle, dissolves readily in water, conducts
electricity well in water, and is salty to the taste. What can we say about calcium chloride?
A. Calcium chloride is held together by ionic bonds
B. Calcium chloride is a non-electrolyte
C. Calcium chloride is held together by covalent bonds
D. Calcium chloride is a weak electrolyte
19. __A__The light spectrum for mercury gives a line at 4.57 x 1014Hz. What is the energy of this
electromagnetic radiation? Plank’s constant = 6.626 x 10-34 J/Hz. Round the answer to the correct number
of significant figures.
A. 3.03 x10-19J
B. 3.03 J
C. 3.03 x1018J
D. 3.03 x1019J
20. __C__Without knowing what chemical you have, how can you safely determine if the chemical is an
electrolyte?
A. Taste the chemical- of it is salty it’s an electrolyte
B. React the chemical with hydrochloric acid
C. Dissolve the chemical in water and test conductivity
D. Burn the chemical under a Bunsen burner to tell the color it gives off
True/False: Determine and indicate if the statement is true or false (each 2 points)
21. __F__A chemist can locate an electron orbiting in the 4p energy level with complete certainty.
22. __T__Schrödinger described the electron with his Wave Function.
Short Answer: Answer each question in the space provided beneath each question. You can use words,
symbols, diagrams, and pictures to answer the question.
23. Two nitrogen atoms come together to form a diatomic molecule of nitrogen gas. Draw the Lewis dot
diagram for nitrogen and explain why it bonds the way it does using the electron configuration. (5 points)
Nitrogen- 1ss2s22p3
Nitrogen has 5 valance electrons (5 electrons in level 2) and must share three electrons to have a
filled octet.
24. Potassium and fluorine react together to form potassium fluoride. Explain why potassium and
fluoride bond the way they do using orbital diagrams or electron configurations. (5 points)
Potassium- 1s22s22p63s23p64s1
Fluorine- 1s22s22p5
↑
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
↑
↑↓
↑↓
Potassium transfers it electron to fluorine to make both a potassium ion and a fluoride ion which
are bonded through electrostatic attraction.
25. Oxygen and potassium fluoride (from questions 23 and 24) represent two different types of bonds.
Explain what type of bonding occurs in each molecule and how these bonds are different. (3 points)
Oxygen forms a covalent bond in its molecule which is formed between two nonmetal and electrons
are shared.
Potaassium fluoride form an ionic bond which is between a metal and a nonmetal and electrons are
transferred.
26. Calculate the number of molecules in 13.6 grams of sulfur dioxide. (3 points)
_____13.6 g_____│______1 mole___________ = 0.212 mole of SO2
│
64.1 g
27. Aluminum metal reacts with iron (II) oxide to for rust in the form of Aluminum oxide. Iron metal is
left as a product of the reaction. Write a balanced equation for this reaction making sure to include correct
formulas and molar coefficients. (5 points)
2Al + 3FeO → Al2O3 + 3Fe
28. An electron in helium has been excited by an electric current to energy level 3. When the electron
comes back down to energy level 1 it releases violet light with a wavelength of 400 nm. What is the
energy in this light wave? Plank’s constant = 6.626 x 10-34 J/Hz. Speed of Light = 3.00 x 108 m/s. (5
points)
First Step: (400 nm) (1 m / 109 nm) = 4.00 x 107 m
Second Step: (4.00 x 107 m) x frequency = 3.00 x 10 8 m/s
frequency = 7.50 x 1014 Hz
Third Step:
(7.50 x 1014 Hz) x (6.626 x 10-34 J/Hz) = 4.97 x 10-19 J
29. (18 points)
C
D
A
B
E
Use the potential energy diagram above to identify and explain how you know:
 When bonds are broken (use the letters)
 When bonds are formed (use the letters)
 Whether the reactants or products are more stable
Rubric:
 When bonds are broken
3 POINTS- Identifies that bonds are broken at letter B or between letters A and C
3 POINTS- Explains that breaking bonds requires energy. The answer may include
information about how it takes energy to get from the reactants to the activation energy
 When bonds are formed
3 POINTS- Identifies that bonds are formed at letter D or between letters C and E
3 POINTS- Explains that energy is released when bonds are formed. The answer may include
information about how energy is released when the products are formed.
 Whether the reactants or products are more stable
3 POINTS- Identifies that the reactants are more table
3 POINTS- Explains that the more stable a compound or atom is the less potential energy it
has. The answer can include that the reactants are lower on the Potential Energy scale (or yaxis) than the products which means the reactants are more stable.
Total Points =18