Untitled - Kelly Walsh High School

142 CHEMISTRY FOR THE UTTERLY CONFUSED
12. Which of the following atoms can never be the central atom in a Lewis
structure?
a. C b. H c. O d. N e. B
13. Draw the Lewis structure of each of the following.
a. H 2S b. CO 2 c. Cl 2O d. NH 4 +
14. Draw the Lewis structure of each of the following.
a. BF 3 b. SF 4 c. XeF 2 d. CS 2 e. SF 6
15. Draw the resonance structures of each of the following.
a. NO 2 b. SO3 c. NO 2
16. Arrange the following in order of decreasing bond length N-N, NæN, and
N=N.
17. Arrange the following in order of increasing bond energy C-O, CæO, and
C=O.
18. Using Lewis symbols, write a balanced chemical equation showing the formation
of lithium fluoride, LiF, from isolated lithium and fluorine atoms.
19. Using Lewis symbols, write a balanced chemical equation showing the formation
of calcium fluoride, CaF 2, from isolated calcium and fluorine atoms.
20. Using Lewis symbols, write a balanced chemical equation showing the formation
of oxygen difluoride, OF 2, from isolated oxygen and fluorine atoms.
21. Draw the Lewis structure of hypochlorous acid, HOCl.
22. Draw the Lewis structure of sodium phosphate, Na 3PO 4. (Be Careful!– this
is tricky.)
ANSWER KEY
1. During chemical reactions, atoms tend to gain, lose, or share electrons in
order to achieve an octet of electrons in their outer shell.
2. Isoelectronic means that the species have the same number and arrangement
of electrons.
3. a. 1 b. 8 c. 7 d. 5 e. 4
4. Electronegativity is a measure of the attractive force that an atom in a compound
exerts on electrons in a bond.
5. e
6. b
7. a. 2 b. 1 c. 0
8. a. 1 b. 2 c. 7
9. The lattice energy is defined as the energy required to separate the ions in
one mole of an ionic solid.
10. c