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Ions and Ionic Compounds
Bonding
Hybridization and VESPR Theory
Short Answer
Predicting Shapes and Drawing Lewis Structures
100
1. The charge on an ion is
a. always positive.
b. always negative.
c. either positive or negative.
d. zero
What is c?
100
6. An ionic bond results from electrical attraction between
a. cations and anions.
b. atoms.
c. dipoles.
d. orbitals.
What is a?
100
11. When a carbon atom's 2s and 2p orbitals hybridize, which orbitals do they form?
a. four sp3
b. two sp3
c. four sp
d. two sp
What is a?
100
16. What is meant by sp3 hybridization?
One s orbital and three p orbitals combine to form four hybridized bonding orbitals of equal energy.
100
21. Use VESPR theory to predict the molecular shape of the following molecule:
carbon dioxide (CO2)
What is linear?
200
2. Which formula listed below represents a polyatomic ion?
a. HCO3-
b. H2SO4
c. Cl-
d. Na+
What is a?
200
7. A covalent bond is formed when two atoms
a. share an electron with each other.
b. share one or more pairs of electrons with each other.
c. gain electrons.
d. gain and lose electrons
What is b?
200
12. Which type of hybrid orbitals do oxygen atoms form in water molecules?
a. sp4
b. sp3
c. sp2
d. sp
What is b?
200
17. Explain why most metals are malleable and ductile but ionic crystals are not.
Metals are malleable and ductile because one plane of metal atoms can easily slide past another without breaking any bonds. The shifting layers in an ionic crystal cause a large buildup of repulsive forces that eventually can make the layers come apart.
200
22. Use VESPR theory to predict the molecular shape of the following molecule:
methane (CH4)
What is tetrahedral?
300
3. The only property listed that is not characteristic of ionic compounds is
a. high melting point.
b. hardness.
c. lack of crystal structure.
d. brittleness.
What is c?
300
8. As the electronegativity difference between bonded atoms decreases, the bond becomes more
a. covalent
b. ionic
c. metallic
d. Both (b) and (c)
What is a?
300
13. According to VSEPR theory, what is the shape of a molecule of CS2?
a. linear
b. bent
c. trigonal-planar
d. tetrahedral
What is a?
300
18. Explain the intermolecular force that contributes to the high boiling point of water.
Hydrogen bonding, a particularly strong dipole-dipole force, causes a strong attraction between a hydrogen atom of one water molecule and the unshared electron pair of an adjacent water molecule.
300
23. Draw the Lewis structures for the following substance.
nitrogen molecule, N2
400
4. The melting points of ionic compounds are higher than the melting points of molecular compounds because
a. ionic substances tend to vaporize at room temperature.
b. ionic substances are brittle.
c. attractive forces between ions are greater than the attractive forces between molecules.
d. the numbers of positive and negative charges are equal in an ionic compound.
What is c?
400
9. Even though the following molecules contain polar bonds, the only polar molecule is
a. CCl4
b. CO2
c. NH3
d. CH4
What is c?
400
14. According to VSEPR theory, what is the shape of a molecule of NBr3
a. bent
b. trigonal-planar
c. tetrahedral
d. trigonal-pyramidal
What is d?
400
19. Compound A has a higher melting point and boiling point than compound B. At the same temperature, compound B vaporizes faster than compound A. Which of these compounds would you expect to be ionic? Why?
Compound A is probably ionic. The ionic attraction is stronger than intermolecular attractions found in covalent compounds, resulting in higher melting and boiling points and requiring more energy for vaporization.
400
24. Draw the Lewis structures for the following substance.
carbon tetraiodide, CI4
500
5. The crystal structure of an ionic compound depends on the
a. sizes of the cations and anions.
b. ratio of cations to anions.
c. masses of the cation and anion.
d. Both (a) and (b)
What is d?
500
10. As atoms bond with each other, they
a. increase their potential energy, thus creating less stable arrangements of matter.
b. decrease their potential energy, thus creating less stable arrangements
c. increase their potential energy, thus creating more stable arrangements of matter
d. decrease their potential energy, thus creating more stable arrangements of matter.
What is d?
500
15. In which of the following compounds has the central atom not formed sp3 hybrid orbitals?
a. CCl4
b. CO2
c. PCl3
d. NH3
What is b?
500
20. Explain why some molecules are best represented by resonance structures and to what degree do these structures indicate the actual structure of the molecule.
Some molecules and ions cannot be adequately represented by a single Lewis structure. The actual structures of these compounds lie somewhere between the resonance structures.
500
25. Draw the Lewis structures for the following substance.
water molecule, H2O