5/17/2015
Review Topic 4: Electron Configurations and Lewis Structures
Name: Score: 17 / 17 points (100%)
Review Topic 4: Electron Configurations and Lewis Structures
Multiple Choice
Identify the choice that best completes the statement or answers the question.
B 1. An element has an electron configuration of 1s22s22p63s2. Which of these will be in the same group as
this element?
a. 1s22s22p6
b. 1s22s22p63s23p64s2
c. 1s22s22p63s1
d. 1s22s22p63s23p6
ANSWER: B
Groups are the columns and this is the only on that ends with s2
POINTS: 1 / 1
D 2. One indicator that electrons in atoms are limited to specific energy levels is that —
a. atoms move faster when heated
b. the light given off by atoms is all at the same wavelength
c. the Doppler effect shows a shift in wavelength for H­atom light
d. light emitted from excited atoms occurs only at specific wavelengths
ANSWER: D
atoms move faster when heated ­ true but doesn’t indicate specific energy levels
the light given off by atoms is all at the same wavelength ­ every atom has its own
wavelengths, not the same
the Doppler effect shows a shift in wavelength for H­atom light ­ the Doppler effect deals
with sound, not light
light emitted from excited atoms occurs only at specific wavelengths ­ this is the one and the
reason we can conduct a flame test.
D 3. POINTS: 1 / 1
ns2 np3
Which of these elements is found in a family with the above electron configuration?
a. Al
c. Si
b. Sr
d. Sb
ANSWER: D
n is a random number, in this case it would represent 5. The important
information is p3, which means we are in group 15.
POINTS: 1 / 1
A 4. The Lewis electron dot system represents electrons in the ­
a. outer energy level
c. middle level
b. inner level
d. core level
ANSWER: A
This is talking about Lewis Dot Formulas, which the dots represent valance
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Review Topic 4: Electron Configurations and Lewis Structures
electrons or outer electrons
POINTS: 1 / 1
D 5. The elements that are characterized by having only five electrons in the p sublevel belong to which
family of elements?
a. Transition
b. Alkali
C 6. c. Noble gas
d. Halogens
ANSWER: D
Transition ­ These have incomplete d
Alkali ­ These have 1 in the s sublevel
Noble gas ­ These have 6 in the p sublevel
Halogens ­ These have 5 in the p sublevel
POINTS: 1 / 1
If the above diagram were the correct representation for the Lewis structure of a molecule, then the X
would be representative of the element ­
a. oxygen
c. nitrogen
b. fluorine
d. sulfur
ANSWER: C
If you add up the total number of electrons, we are dealing with 10 electrons. [4 dots + 3 lines (x2 electrons)]. We have the same element twice so, 10/2 = 5
valence electrons, which leads to nitrogen.
POINTS: 1 / 1
C 7. Which of these elements contains four valence electrons?
a. Helium
c. Carbon
b. Beryllium
d. Oxygen
ANSWER: C
Helium ­ 2
Beryllium ­ 2 (Group 2)
Carbon ­ 4 (Group 14)
Oxygen ­ 6 (Group 16)
POINTS: 1 / 1
C 8. Which of the following orbital diagrams is incorrect because it violates Hund’s rule?
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Review Topic 4: Electron Configurations and Lewis Structures
a.
b.
c.
d.
ANSWER: C
Hund’s Rule ­ spread them out before pairing them together.
POINTS: 1 / 1
C 9. What is the correct Lewis dot structure for arsenic?
a.
c.
b.
d.
ANSWER: C
POINTS: 1 / 1
D 10. What shape does the molecule BF3 have?
a. Bent
b. Linear
c. Tetrahedral
d. Trigonal planar
ANSWER: D
The B will be surrounded by three F’s which would make it either trigonal
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Review Topic 4: Electron Configurations and Lewis Structures
planar or trigonal pyramidal. Since trigonal pyramidal is not an answer, it has
to be trigonal planar.
POINTS: 1 / 1
D 11. Which of the following is the correct molecular shape of CH4?
a. Bent
c. Pyramidal
b. Linear
d. Tetrahedral
ANSWER: D
The C is surrounded by 4 hydrogens, which make it tetrahedral.
POINTS: 1 / 1
B 12. With n representing the outermost energy level, the electron configuration for that level for elements in
Group 14 is ­
a. ns2np1
b. ns2np2
c. ns2np3
d. ns2np4
ANSWER: B
All Group 14 have 4 valance electrons, and the only one above with 4 is ns2np2
POINTS: 1 / 1
B 13. What is the electron configuration of scandium (Sc) in Sc(NO3)3?
a. 1s22s22p63s23p64s23d1
b. 1s22s22p63s23p6
c. 1s22s22p63s23p64s2
d. 1s22s22p63s23p63d3
ANSWER: B
The first important thing to remember is it says Sc in this compound, which is
an ionic compound. The you have to remember that Sc would form the cation
(positive part) and according to the formula, it would be a +3. After that, you
have to subtract three electrons from its electron configuration and have the
same configuration as argon (and all noble gases end in p3)
POINTS: 1 / 1
C 14. How many electrons are needed to completely fill the orbitals from 1s to 4p?
a. 7
b. 18
c. 36
d. 46
ANSWER: C
First you have to determine the electron filling order from the picture
1s2s2p3s3p4s3d4p
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Review Topic 4: Electron Configurations and Lewis Structures
Then you have to remember that s gets 2 electrons (from 1 box), p gets 6 (from
3 boxes), d gets 10 (from 5 boxes) (and f would get 14 from 7 boxes)
Replacing this into the information above results in:
2+2+6+2+6+2+10+6 = 36
POINTS: 1 / 1
B 15. How many valence electrons does a neutral atom of silicon have?
a. 3
c. 5
b. 4
d. 6
ANSWER: B
Group 14 elements all have 4 valence electrons (remember, ignoring 1 in front
of 14 gives you valance electrons for groups 13­18)
POINTS: 1 / 1
A 16. Which structure represents a nonpolar molecule?
a.
c.
b.
d.
ANSWER: A
To be nonpolar, the molecule has to be symmetrical. The only symmetrical molecule is a.
b is not symmetrical due to the alcohol group (OH) being different from the
rest of the Hs
c is not symmetrical due to the Cl being different from the Hs
d is not symmetrical due to the O being different from the Hs
POINTS: 1 / 1
Numeric Response
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Review Topic 4: Electron Configurations and Lewis Structures
Directions: Type your answer in the box. Use “+” and “­” for the electrical charge.
17. What is the oxidation number of an oxide ion?
RESPONSE: ­2
ANSWER: ­2
or 2­
(oxide is the ionic version of oxygen and group 16 on the periodic table form
­2 ions due to the fact that this column has 6 valence electrons and need to
gain 2 more electrons. Since electrons are negative, gaining two makes a
negative 2 charge).
POINTS: 1 / 1
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