PRACTICE EXAM 3 – ANSWER KEY
Part 3: Memorized Material

I highly suggest that you bring pencil and big block eraser for Part 3 of the Exam.

You may use your calculator for Part 3 of Exam 3.

You may use the Periodic Table from Part 2.

You may use the Polyatomic Ions Sheet from Part 2.

You will not have access to model kits for Exam 3.

Electronegativity Values will be given when they are needed.

Timing

Mastery = 25 min

Competency = 40 min
PART 3C TRUE/FALSE

If the statement is True, write “T” in the first box.

If the statement is False, write “F” in the first box.

If the statement is False, find the word in the sentence that is underlined. Cross out the
underlined word. In the box provided, write the word that will make the statement true.
F
41)
At room temperature, mercury is a monatomic solid.
liquid
F
42)
At room temperature, the only element that is a diatomic solid is bromine.
iodine
T
43)
Iron has two valence electrons.
You don’t have to show work, but 
Fe: 1s2 2s2 2p6 3s2 3p6 4s2 3d6
T
44)
As you move from left to right on the periodic table, atomic radius increases.
F
45)
The AXE notation for a trigonal bipyramidal molecule is AX4.
tetrahedral
T
46)
The bond angle for a molecule for a bent molecule is <109.5°
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Part 3D: Art/Diagrams

Make sure to write lone pair electrons when they are present.

Remember to write brackets when necessary.
47)
Sketch the Lewis Dot Structure for the bromine atom.
48)
Sketch the Lewis Dot Structure for the sodium atom.
Na
49)
Sketch the Lewis Dot Structure for C3H6. You may not write cyclical structures.
50)
Sketch the Lewis Dot Structure for carbon monoxide, CO.
51)
Sketch the Lewis Dot Structure for the phosphonium ion: PH4+
H
|
H − P − H
|
H
+
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53)
Answer the following questions about the diagram below:
H
H
H
H
H
AXE NOTATION
53A)
trigonal bipyramidal
<109.5°
AX3E1
53B)
tetrahedral
109.5°
AX4
53C)
bent
<109.5°
AX2E2
H
N
C
BOND ANGLES
H
C

O
H

H
C
GEOMETRY
*Clarification
53a)
Assume that the nitrogen atom is the central atom.
53b)
Assume that the carbon atom is the central atom.
53c)
Assume that the oxygen atom is the central atom.
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Information for Question 54
ELEMENT
H
C
O
N
F
Cl
Br
I
ELECTRONEGATIVITY VALUE
2.1
2.5
3.5
3.0
4.0
3.0
2.8
2.5
54)
54A)



For the following pairs of covalently bonded atoms:

Write whether the covalent bond is polar or non-polar

If the covalent bond is polar, indicate the polarity of each atom with + and − notation.
C −



54C)



H −



55)
−
O
polar
(Electronegativity for oxygen) – (Electronegativity for hydrogen) = 3.5 – 2.1 = 1.4
Since the difference is between 0.4 and 1.7, the bond is polar.
Since oxygen has the higher electonegativity value, it is slightly negative; hydrogen is slightly
positive.
C −
Br
polar
(Electronegativity for bromine) – (Electronegativity for carbon) = 2.8 – 2.5 = 0.3
Since the difference is below 0.4. The bond is non-polar.
Delta notation is not applied.
+
54D)
non-polar
(Electronegativity for Carbon) – (Electronegativity for Hydrogen) = 2.5 – 2.1 = 0.4
Since the difference is in the 0 to 0.4 (inclusive) range, the bond is non-polar.
Delta notation is not applied.
+
54B)
H
I −
−
N
polar
(Electronegativity for nitrogen) – (Electronegativity for iodine) = 3.0 – 2.5 = 0.5
Since the difference is between 0.4 and 1.7, the bond is polar.
Since nitrogen has the higher electonegativity value, it is slightly negative; iodine is slightly
positive.
The bond below represents is polar covalent. Write the correct arrow notation to indicate the
direction of polarity.
F −
Cl
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56)
Rewrite the following elements in order of increasing atomic radius (smallest to largest).
Si
F
57)
F
Cl
Si
Cl
Mg
Rewrite the following elements in order of increasing metallicity (less metallic to most
metallic).
Cs
Be
58)
Mg
Fr
Be
Ba
Cs
Ba
Fr
Define the term “electronegativity.” You do not need to supply any examples.
Electronegativity is the tendency for an atom to attract the electron density in a
covalent bond.
59A)
Define the term “isolelectronic.”
Isoelectronic means that two particles have the same electron configuration.
59B)
Write the electron configuration for argon.
Ar: 1s2 2s2 2p6 3s2 3p6
59C)
Write the electron configuration for the sulfide anion.
S : 1s2 2s2 2p6 3s2 3p4. Sulfur gains two electrons to become sulfide. So...
S2− : 1s2 2s2 2p6 3s2 3p6
59D)
Write the electron configuration for the sodium cation.
Na : 1s2 2s2 2p6 3s1. Sodium loses one electron to become the sodium cation. So...
Na+ : 1s2 2s2 2p6
59E)
Are any of the particles in 59b, 59c, and 59d isoelectronic? If so, which ones?
Yes, the sulfide anion and the argon atom are isoelectronic.
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60)
In an ionic compound, does aluminum need a Roman numeral to indicate its charge? Why or
why not?
61)
What is the charge of bismuth in Bi2S3?
3+
62)
What is the charge of iron in iron(III) sulfate?
3+
63)
What is the charge of cobalt in CoS3?
6+
64)
What is the charge of in manganese is Mn2O7?
7+
QUESTION 65
Question 65 will be a short essay question (five to eight sentences). The topic can be any one of
the following:

Explain why atomic radius decreases as you go from left to right on the periodic table. If you
need two elements to use in your explanation, use the Bohr Models of oxygen and beryllium.

Explain why ionization energy increases as you go from left to right on the periodic table. If
you need two elements to use in your explanation, use the Bohr Models of oxygen and
beryllium.

Explain why ionization energy decreases as you move from the top of the periodic table
(Period 1) to the bottom of the periodic table (Period 7). If you need two elements to use in
your explanation, use the Borh Models of lithium and rubidium.
This information is in your notes and in the text.
You are finished with Part 3 of the Exam.
 If you do not wish to do the Extra Credit, turn
in Part 3 and all of the reference tables.
 If you wish to do the Extra Credit, keep the
reference tables, turn in Part 3, and ask for
the Extra Credit.
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