3
17. Write the formula or name the compound:
Aluminum Phosphate ____AlPO4______________
H2Si
___Dihydrogen monosilicide______
Tetrasulfur decoiodide
PbS
___Lead (II) sulfide _____________
___S4I10______________
Short answer:
18. What are the two factors that affect if a molecule is polar or non-polar? Be Specific.
1) the presence of polar bonds (dipoles)
2) the arrangement of polar bonds (dipoles)

If the molecule is symmetrical, dipoles cancel each other  non- polar molecule

If the molecule is asymmetrical, dipoles cannot cancel each other  polar molecule
19. What is the difference between ionic bond, non-polar covalent bond, and polar covalent bond?
Ionic Bond – electrons transfer from metals to non-metals.
Non-polar Covalent Bond – electrons shared equally between non-metals / metalloids.
Polar Covalent Bond – electrons shared equally between non-metals / metalloids
20. Draw the Lewis Structure of CF4. Draw the dipoles if there are, tell if the bond is polar, and if the
molecule is polar.
Bond: Polar
Molecule: Non-polar (dipoles cancel
each other)
4
Open Response:
21. Incorrect Lewis dot structures for CO, O2, and C2H4 are shown in the figures below.
a. Select two of these Lewis dot structures and explain why each is incorrect.
b. In your Student Answer Booklet, draw the correct Lewis dot structure for each compound you
selected in part (a).
a.
CO is incorrect because there should be [1(4) + 1(6)] = 10 valence electrons available, but the picture
only has 8 valence electrons.
O2 is incorrect because there should be [2(6)] = 12 valence electrons available, but the picture has 14
valence electrons.
C2H4 is incorrect because C and C have too many valence electrons (too many bonds); or there should be
[2(4) + 4(1)] = 12 valence electrons, but the picture has 14 valence electrons.
[You may use NASL method to explain all three cases]
b. Show NASL steps to find out how many bonds and lone pairs.
22. Carbon (C) reacts with bromine (Br) to form carbon tetrabromide (CBr4).
a. Draw the Lewis dot structures for carbon (C) and bromine (Br).
b. Draw the Lewis dot structure for carbon tetrabromide (CBr4).
c. Identify the shape of the CBr4 molecule as predicted by valence-shell electron-pair repulsion
(VSEPR) theory and explain why CBr4 has this shape.
a.
c. Tetrahedral, it has 1 central atom with 4 bonded atoms,
totally there are 5 atoms, and there is no lone pair
around central atom (C).
b.