H CH 7 HOMEWORK
Draw Lewis Structures for the following:
Single Bonds  H2O*, C2H6, CCl4*

H – O 
|
H
H H
| |
H–C–C–H
| |
H H

Cl 
 | 
Cl – C – Cl 
 | 
Cl

Double Bonds  CH2O*, CO2*, COCl2





H – C = O 
O=C=O
 Cl – C = O 
|


 |
H
Cl
Triple Bonds  C2H2

H-CC-H
Polyatomic Ions  NH2-1*, CN-1, NO3-1*

 


H-N-H [N –1] CN [C –1] O – N =O  [2 O’s –1; N +1]


|
 O  resonance

Miscellaneous  H2O2, CS2*, CO, N2H2, O3*, N2F4, IO3-1*, HCN*, N2O*, SiO4-4*
 
H–O–O–H
 


S = C = S 
 
CO [C –1; O +1]
  
O – O = O  [1st O –1; 2nd O +1]


H–CN
 
H – N=N – H
   
F – N – N – F 
 |
| 
FF
 
  
O – I – O  [I +2
 |  O’s -1]
 O 


 O


 | 
N=N=O [1st N –1; 2nd N +1] O – Si – O  [O’s –1]
 | 
 O 

Determine the shape, bond angle, polarity, and type of hybridization of the above
compounds with an (*) beside them.
.
1. single bonds  H2O
CCl4
Bent, 109.5, polar
Tetrahedral, 109.5, nonpolar
2. Double bonds  CH2O
CO2
Triangular Planar; 120, polar
linear, 180, nonpolar
3. Polyatomic ions  NH2-1 bent; 109.5, polar
NO3-1 triangular planar; 120, nonpolar
4. Miscellaneous  CS2
O3
IO3-1
HCN
N2O
linear, 180, nonpolar
bent, 120, nonpolar
triangular pyramidal, 109.5, polar
linear, 180, polar
linear, 180, polar/nonpolar
Review:
1. What is the relationship between electronegativity difference and type of bond?
Higher the difference, the more ionic the bond
2. What is the meaning of the term polar as applied to chemical bonding?
There is a positive and negative end
3. What one thing will determine if atoms will form chemical bonds?
Their potential energies are decreased
4. What is meant by an unshared or lone pair of electrons?
A pair of electrons no involved in bonding
5. Determine the number of valence electrons in each of the following:
1
2
3
7 5
8
4
6
H Mg Al F N Ne C O
6. What is the difference between a single, double, and triple bond?
The number of electrons being shared
7. What is a polyatomic ion?
A group of atoms with a charge
8. What is an ionic compound?
Formed by 1 atom gaining and 1 atom losing an electron
9. In what form do most ionic compounds occur?
A crystal
10. What is a formula unit? How many K+1 and S-2 ions would be in one formula unit of
the ionic compound formed by these ions?
Smallest whole number rations of ions in a lattice; 2 K+1 : 1 S-2
11. In general, how do ionic and molecular compounds compare in terms of physical
properties? Ionic has high MP, will conduct electricity in solution, is brittle
12. What is a metallic bond?
A bond formed between positive metal ions and free electrons
13. What are hybrid orbitals?
Orbitals that have been mixed to allow for e- to be as far apart as possible.
14. What are intermolecular forces?
Attractive forces that exist between molecules
15. List the three intermolecular forces and describe them.
H bonding – between H on 1 molecule and an unshared pair of electrons on a F,N,or O
Dipole-Dipole – Attraction of (+) end of polar molecule to the (-) end of another polar
molecule
Van der Waals – similar to dipole-dipole but produced by temporary dipoles from
unequal distibution of electrons
16. What 2 things determine the polarity of a molecule?
Shape and types of bonds
17. Determine the resulting bond type and draw the dipole (if applicable) for each of the
following if bonded together.

+
avg (1.7)
+ avg (1.89)
H and I polar (.46)
Ba and S
ionic (1.69) Br and K ionic (2.14)

Avg(2.55)

Zn and O polar (1.79)
I and N
polar (.38) S and I nonpolar(.08)
18. How many sigma and pi bonds would be in a molecule of COCl2?
3 sigma, 1 pi
19. Use orbital notation to show the bonding in H2O2 and CS2, KCl.
see me
20. What group would element “X” belong to: (Assume that all atoms have an octet.)
X—Br
7
X—X—X (-2 on entire structure)
6
21. Do the following represent resonance structures or structural isomers?
O
O
||
|
resonance
H—C
AND
H—C
|
||
O
O
22. What type of hybridization is represented in the molecules in #21?
Sp2
23. Draw the Lewis structure for SF4.
F
| 
F–S–F
|
F
24. Which of the following sets of molecules would exhibit stronger Van der Waals
forces and why?
A
X
X X
X
A)
X—X—X—X—X
B)
\ / | \ /
----------------------X
X
X—X—X—X—X
/ \ | / \
X
X X
X
|
25. An article in the Journal of Chemical Education was entitled "Solving the Mystery
of Fading Fingerprints." It dealt with a crime where an 8-year-old girl was kidnapped in
the south during the summer and eventually escaped. The kidnapper was finally caught
four days later but when his car was searched for fingerprints of the victim, all that was
found were fingerprints from the kidnapper. Fingerprints consist primarily of water, but
also contain oils (carbon chains), fatty acids (carbon chains), esters (carbon chains), salt,
urea, and amino acids. What is a possible explanation for the reason that the girl's
fingerprints were not found in the car but his were? Yes, she was in the car and did touch
parts of the car and yes, she also has hands