EXAMPLE Predicting Types and Strengths of Attractions Between Particles:
For each of the following substances, write the name for the type of particle that forms its basic structure and the name of the primary type of attraction between these particles. From each pair of substances, choose the one that you expect to have the stronger interparticle attractions.
ethylene, C2H4 (used to make polyethylene plastic)
b. sodium fluoride, NaF (used to fluoridate municipal water)
ammonia, NH3 (used to make fertilizers)
methanol, CH3OH (used as a solvent and a fuel)
e. 1-propanol, CH3CH2CH2OH
waxes and vegetable oils)
in the diamond form, C(dia) (used
for windows in space probes)
Ethylene, C2H4 and propylene, C3H6 are both hydrocarbons, so they are nonpolar
molecular substances with London forces operating between the molecules. Larger
molecules exert stronger London forces, so the attractions between C3H6
molecules are stronger than those between C2H4 molecules.
Sodium is a metal, and fluorine is a nonmetal, so we predict that NaF is an
ionic compound, held together with ionic bonds. The compound NF3 is a molecular
substance with an asymmetrical distribution of polar bonds, so it is a polar
molecular compound with dipole-dipole attractions between the molecules
(enhanced by London forces). Ionic
bonds are stronger than dipole-dipole attractions, so NaF has the stronger
attractions between particles.
Ionic bonds are stronger than dipole-dipole attractions, so NaF has the stronger attractions between particles.
formula NH3 represents a molecular, substance possessing N-H bonds, so it is a
polar molecular compound with hydrogen bonds between the molecules (enhanced by
London forces). Methane is a hydrocarbon, so it is a nonpolar molecular
substance with London forces operating between the particles. For molecules of
about the same size, hydrogen bonds are stronger than London forces, so NH3 has
the stronger interparticle attractions.
is an alcohol, and alcohols are polar molecular compounds with hydrogen bonds
that link the molecules together (enhanced by London forces). Potassium atoms
are held together by metallic bonds. Metallic bonds are stronger than hydrogen
bonds, so potassium has the stronger interparticle attractions.
substances are alcohols, which are polar molecular compounds. The primary
attractions between alcohol molecules are hydrogen bonds, but London forces also
play a part. The larger 1-propanol molecules have stronger London forces between
and fluorine are both nonmetallic elements. Carbon in the diamond form is
composed of atoms held together by covalent bonds. Fluorine, F2, is composed of
molecules held together by London forces. The covalent bonds in a diamond are
much stronger than the London forces between F2 molecules.