CHEMISTRY 1
UNIT 8, ELECTRON DOTS AND VSEPR THEORY
Unit 8 Guiding Questions:
1. What are some ways to represent how elements combine to make compounds?
2. How do we use Lewis Dot structures to represent chemical bonds?
3. How does the VSEPR theory relate to intermolecular forces of attraction?
4. What is hydrogen bonding and what is the most common example of it?
5. What is the difference between intramolecular and intermolecular forces of attraction?
Key Vocabulary Terms (Mostly chapter 9 in text):
Aqueous solution
solute
VSEPR theory
London Dispersion Forces
Hybridization
dipole-dipole interaction
van der Waals Forces
Lewis Electron Dot Structures
1.
solvent
polarity
hydrogen bonding
What is the difference between metallic, ionic, and covalent bonding?
2. On what two things does the strength of an ionic bond depend?
3. What are some examples of covalent bonds in nature?
4. How is electronegativity used to determine the kind of bond between two atoms?
5.
Atom
Number of Valence
Electrons
Number of Electrons
Needed to Fill Valence Shell
Bonding Capacity
Carbon
Nitrogen
Oxygen
Halogens
Hydrogen
6. Based on trends in electronegativity, which of the following substances show the most even
distribution of valence electrons? Explain your choice.
Ammonia (NH3)
Silver sulfide (Ag2S)
Phosphorus pentachloride (PCl5)
7. Draw the Lewis dot structures for the following neutral atoms.
a. Sodium
b. phosphorus
c. krypton
d. aluminum
8. What are the steps for drawing Lewis Dot structures? (See Handout)
9. Create Lewis dot diagrams for the following molecules:
a. hydrogen sulfide
b. nitrogen trichloride c. carbon dioxide
10. Draw structural formulas (using lines to show bonded electron pairs) for the compounds below.
b. Hydrogen sulfide
b. nitrogen trichloride c. carbon dioxide
11. Which molecules in questions 9 and 10 include double bonds? How many pair of electrons are
shared in a double bond?
12. How many pair of electrons are shared in a triple bond?
13. List the 7 diatomic molecular elements, also known as the stupendous seven and give their
electron dot structures.
14. What do the letters VSEPR stand for? What is the basic assumption of this theory?
15. Draw the Lewis dot diagram for a water molecule. Draw (as well as you can) the three
dimensional shape of a water molecule. How does the angle between the bonded hydrogens
differ between the two representations?
16. Why is the bond angle in a trigonal pyramidal molecule different from that in a tetrahedral
molecule?
17. Complete the following table. Use the diagrams below the table to identify the answers for the
final column.
Formula
Dot structure
Number of
Number of
Name of
Diagram of
of
bonding
nonbonding
Shape
shape from
central atom
electrons
electron pairs
below
SbH3
Cl2O
BeH2
SiF4
18. List the kinds of intramolecular and intermolecular forces of attraction from strongest to
weakest.
19. What is a van der Waals force? Is it an example of a chemical bond? Why or why not?
20. For different substances of similar molar mass, which type of intermolecular force is weakest?
Give an example of a molecule that would exhibit this force.
21. What makes a molecule polar?
22. Give two examples of polar molecules that contain polar bonds. Give two examples of nonpolar
molecules that contain polar bonds.
23. What is a temporary dipole? What types of molecules are capable of having temporary
dipoles? What is the name of the van der Waals force that involves temporary dipoles?
24. Why type of intermolecular forces of attraction would be exhibited by each of the following
substances?
a. PF3
b. N2
c. HF
d. BeH2
25. What is hydrogen bonding? Give an example of a substance that would exhibit hydrogen
bonding.
26. The following substances have roughly the same molar mass. Which one is most likely to have
the higher boiling point: H2S, F2, or CO2? Explain your choice.