Download Problem set-Unit 1 Structures

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Problem Set - Structures and Properties Unit v. 0914
Knowledge
Inquiry
/29
Communication
/47
Application
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Knowledge [29 marks]
1. a) Draw energy level diagrams for: [2 marks each]
a) F-
c) N3-
b) Ca
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b) Is calcium paramagnetic or diamagnetic? How do you know?
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2. Write the short form electron configuration for: [2 marks each]
a) Co
b) Yb
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3.
Identify the orbital corresponding to the following quantum numbers:
a) n = 3, l = 2, ml = 1, ms =  ½
_____________
b) n = 5, l = 3, ml = -3, ms =  ½
_____________
c) n = 4, l = 1, ml = -1, ms =  ½
_____________
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4. Rank these bonds from least to most polar: [2 marks]
a) H − I
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b) P − I
c) Si − F
d) Mg − N
e) F − F
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5.
Compare the Lewis structures of the cyclohexane (C6H12) and benzene (C6H6)..
Cyclohexane
Benzene
a) How many sigma bonds
are present in each
molecule?
b) How many pi bonds are
present in each molecule?
c) Based on your analysis,
what hybrid orbitals are
found around each carbon?
d) Based on your analysis,
what molecular geometry
(shape) is present around
each carbon?
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6. Select the substance with the higher melting point and explain the reason.
a) ZnS vs. CH3OH [2 marks]
b) CH4 vs. SiH4 [2 marks]
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Inquiry [47 marks]
7.
Which of the following designations are orbitals that are not possible in wave mechanics? Why?
1d,
4f,
1p,
6d,
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8.
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Write the quantum numbers for the two electrons in a 3s orbital. [2 marks]
2f
9. Explain why there is an exception to the trend in first ionization energy when comparing :
a) Magnesium and Aluminum [2 marks]
b) Phosphorous and Sulfur [2 marks]
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10. Complete the following chart
CH2O
CH3Cl
C2F2
HCN
NCl3
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Lewis Structure
(with dipoles)
[2]
VSEPR shape
name [1]
Bond Angles [1]
Bond Polarity
[1]
Molecular
Polarity [1]
Hybridization
of central atom
[1]
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11. With the help of an energy level diagram, explain the 1+ and 3+ charges on the Tl1+ and Tl3+ ions
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Communication [ 21 marks]
12. The actual electron configuration of chromium is [Ar]4s13d5. Explain why chromium has an
anomalous electron arrangement. [2 marks]
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13. If 6 electrons are to be placed into a d subshell, describe the procedure, including the appropriate
rules. [3 marks]
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14. a) Draw a Lewis structure of these polyatomic ions and indicate their VSEPR shape [3 marks
each]
a) IO4- (periodate ion)
b) SO32- (sulfite ion)
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15. a) Draw a Lewis structure for ethene (C2H4) [1mark]
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Examine the diagram below of the bonding orbitals in ethene (C2H4).
b) Label the types of orbitals [2 marks]
c) Label each sigma and pi bond [2 marks]
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c) ClO2- (chlorite ion)
16. Explain what the chart below is trying to show in terms of boiling point.
Boiling Points of Some Polar and Nonpolar Substances
Substance
HCl
H2S
F2
Ar
Boiling Point (oC)
Molar Mass
(g/mol)
Number of
Electrons
-84.9
36
18
-60.7
34
18
-188.1
38
18
-185.7
40
18
polar
nonpolar
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Application [28 marks]
17. Theories and tools such as VSEPR and the vector addition of bond dipoles are tested by their ability to
predict the actual observed nature of molecules. Explain why the following molecules are polar or nonpolar.
a) beryllium bromide (BeBr2 (s)); non-polar
b) nitrogen trifluoride (NF3 (g)); polar
c) methanol (CH3OH (l)); polar
d) hydrogen peroxide (H2O2); non-polar
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18. Provide ground state and promoted state electron configurations for each of the following
central atoms and indicate the type of hybridization involved when each atom forms a
compound and draw a representation of the hybrid orbitals surrounding the central atom. [4
marks each]
a. carbon in CH4
b. boron in BH3
c. beryllium in BeF2
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19. a) Draw the orbital representation for bonding in propene (C3H6) shown here.
[2 marks]
b) Identify the number of sigma and pi bonds.[2 marks]
c) Identify the type of hybridization around each carbon [2 marks]
d) Predict the shape around each carbon in the molecule based on the
hybridization states of each carbon atom. [2 marks]
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20. Compare the arrangement of carbon atoms, and explain the different properties of graphite
and diamond.
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