ADVANCED HONORS CHEMISTRY - CHAPTER 8
NAME:
COVALENT BONDS
DATE:
VAN DER WAALS WKST # 3 - ANSWERS PART 1 - V16 PAGE:
REMEMBER THE COLOR GRID FOR POLARITY
Area of Partial
Neutral
Area of Partial
Positive Charge
(Switzerland)
Negative Charge
FOR EACH QUESTION LIST ONLY THE STRONGEST INTERPARTICLE FORCE PRESENT.
MAKE SURE TO ASK YOURSELF (SELF?):
1. IONIC, METALLIC, OR MOLECULAR?
2. IF MOLECULAR, POLAR OR NONPOLAR?
1. Ethane, CH3CH3, is a symmetrical hydrocarbon molecule, which means it is nonpolar. When two nonpolar
molecules come together dispersion forces holds them together.
1
2. All salts, including barium sulfate (BaSO4), are ionic and water, of course, is a dipole. Therefore, the force
holding them together is an ion-dipole force.
3. First you must realize oxygen is a diatomic molecule. Because it is composed of two atoms of the same
element it must be nonpolar. When two nonpolar molecules come together they are held together by
dispersion forces.
Nonpolar molecule
Nonpolar molecule
Temporary Dipole
Dispersion
Force
Induced Dipole
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4. The force between two water molecules is a perfect example of hydrogen bonding (stupid name).
Remember: hydrogen bonds ARE NOT actually bonds and hydrogen must be covalently bonded to a NOF
in order to create the resulting interparticle force we call a hydrogen bond. By the way you will get this
wrong on the test.
For Water See Question #2 Above
5. First you must do nomenclature (told you it would never go away) for the hydrogen chloride, which is HCl.
Then determine if it’s polar or nonpolar, which in this case it’s polar. Neon is nonpolar because it is a single
atom. So now you have a dipole and a nonpolar molecule, which will lead you to discover this force is
dipole-induced dipole.
6. First you must determine if ethanol, CH3CH2OH, is molecular or ionic. Ethanol is, of course, molecular
(composed of nonmetals). Now determine whether it is polar or nonpolar, in which case you will find
ethanol to be polar (see models below). At this point it appears to be a dipole-dipole, however, there’s an H
connected to a NOF, which means that the major interparticle forces are hydrogen bonds.
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7. First you must determine if CO2 is polar or nonpolar. It’s nonpolar due to its linear shape and symmetrical
structure. The forces between two nonpolar molecules are dispersion forces.
8. NaCl or table salt is ionic. HF is a polar molecule, which means the resulting forces are ion-dipole forces.
9. The first step is nomenclature (still not going away). Ammonium chloride comes out to be NH4Cl and
boron trifluoride is BF3. By now you should notice that any cation and anion combined is a salt or ionic
compound, which means ammonium chloride is a salt. Now determine if BF3 is polar or nonpolar (welcome
back to Lewis structures). Since it’s electronic and molecular geometries are trigonal planar, it is
symmetrical and thus, nonpolar. This means you have an ion and a nonpolar molecule which results in a
ion-induced dipole.
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10. Here you have chlorodifluoromethane, CHClF2, which after doing the Lewis structure (seem familiar?), you
find it to be a polar molecule (see structures below). When two polar molecules come together you form
dipole-dipole forces. (Instructor’s note: What are you doing with a bottle of chlorodifluoromethane?)
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