Unit 9 Bonding – Review Sheet
Covalent bonding. For the following molecules, determine their:
a.
b.
c.
d.
Lewis structure
VSEPR geometry and bond angle.
Polarity
and determine if they will dissolve in water or not.
1. SiF4
2. OCl2
3. NF3
4. CS2
5. OPBr3
6. H2CO
7. CH2Cl2
8. ICN
9. How does bonding cause some reactions to be exothermic and others endothermic?
a. If energy of bonds in reactants > energy of bonds in products = exothermic
b. If energy of bonds in reactants < energy of bonds in products = endothermic
Ionic Compounds
1. Describe how bonding works in an ionic compound. Use NaCl as an example.
a. First the Na atom transfers an electron to the more electronegative Cl atom, forming a
Na+ cation and Cl- anion. Then, these ions form an ionic bond due to their natural
electrostatic attraction for each other.
2. How does this bonding result in a crystal lattice structure? For example, how are the ions
arranged in NaCl? Draw a picture to help show your concept.
a. The Na and Cl ions pack themselves as close as possible due to their attractions. This
results in a 3D geometric pattern known as the crystal lattice.
3. How does ionic bonding cause the main physical properties of ionic compounds?
a. The strong bonds in the crystal lattice result in ionic compounds being solid at room
temperature and very hard. They are brittle because when hit, the ions will shift and
similarly charged ions will repel each other and split the crystal apart.
Metallic compounds
1. Describe the electron sea model. Use iron as your example (draw a picture).
a. In a metal like iron, the metal atoms give up their valence electrons to be generally
shared with all metal atoms in the sample. Iron will give up its 2 valence electrons to
this sea of electrons.
2. What is an alloy? Provide a specific example.
a. An alloy is a physical mixture of different metals (and sometimes non-metals). The
mixed atoms have different properties than the metals on their own. Sterling silver,
steel and bronze are examples.
Intermolecular forces
1. Which of the three IMFs is the strongest? Why?
a. Hydrogen bonding due to the large electronegativity differences between H and F, O
and N atoms resulting in a large dipole moment.
2. How relatively strong are the IMFs compared to ionic or covalent bonds?
a. Hydrogen bonds are about 10% of covalent or ionic bond strength, but many dipoledipole forces are much weaker and London Dispersion forces can be only 1% or less of
the covalent bond strength.
3. What is meant by “like dissolves like”?
a. Polar solvents dissolve polar solutes (ionic compounds and polar molecules) and nonpolar solvents dissolve non-polar solute molecules.
4. What is the strongest IMF in the following:
a. PF3
b. O3
c. CH3Cl
d. HONO2