Focus Questions

January 27

p. 580

1.    On your paper, draw a horizontal line.  On one end of the line write the words "ionic bond".  On the other end write the words "covalent bond".  Using the information provided in Figure 13.3, place the following bonds at the appropriate location on your line. 

Na-Cl, Al-Cl, Si - Cl, P - Cl, S - Cl, Cl - Cl

How many of these bonds are polar covalent?

p. 584-587: start reading at the bottom of the page, the paragraph that starts with "Polyatomic molecules . . ." up to section 13.4

2.    Draw the LDS for the following compounds and use VSEPR to determine their shape.  Then, determine which of the compounds will be polar.

AlCl₃, SiCl₄, PCl₃, PCl₅, SCl₂, SCl₄, Cl₂

p. 746 - 750

3.    As you read page 746, be aware that DH° is a measure of how much energy is required to facilitate the change.  Clearly, it takes much more energy to change one mole of liquid water to vapor water than it takes to change one mole of solid water (a.k.a., ice) to liquid water.  What does this suggest about liquid water?

4.    What is the difference between intramolecular forces and intermolecular forces?

5.    What is a dipole-dipole attraction and how strong is it relative to a covalent bond?

6.    Why are hydrogen bonds stronger than most dipole-dipole attractions?

7.    How does lowering temperature increase the likelihood of induction of an instantaneous dipole?

8.    Polarizability is the ability of a compound to acquire an induced dipole.  Xenon is much bigger than helium, i.e., its outermost electrons are a lot further from the nucleus and they are spread out over a much larger sphere than helium's outermost electrons.    Why does it make sense that xenon is more polarizable than helium?

16.2

9.    The properties of a given liquid depend largely on the strength of their intermolecular forces.   What is the relationship between surface tension and intermolecular forces?  What is the relationship between viscosity and intermolecular forces?

p. 784 - 787

10.    What is the relationship between intermolecular forces and vapor pressure?

11.    If you put water into a flask and cork the flask, some of the water will evaporate.  Is this gaseous water the only kind of gas molecule in the flask?  Is the vapor pressure of water equal to the total pressure in the flask?

12.    Explain why vapor pressure increases with temperature.

skip from "The quantitative nature of temperature. . ." resume reading at "Changes of State", p. 788 - 791 (end of section)

13.    What's happening on the horizontal lines in figure 16.50?

14.    What happens to the temperature of ice while it is melting to liquid?  What happens to the temperature of water while it is boiling to become vapor?

15.    Give the definition of normal boiling point.