SI Practice Exam 4
CHM 111 Summer 2013
SI Leader: Kristen Kelly
Equations:
Formal Charge = Valance - #nonbonding electrons - #bonds
1. Define the following:
a. Resonance hybrid
b. Negative Electron Affinity
c. Octet Rule
2. State whether the following molecules are ionic, polar covalent, or non-polar covalent.
a. CBr4
c. NH3
b. KCl
1
SI Practice Exam 4
CHM 111 Summer 2013
SI Leader: Kristen Kelly
3. Write the electron configuration for the following:
a. V
b. Ru3+
c. Ga3+
4. Ionization energy increases going to the right on the periodic table and decreases going down. However, there are
some exceptions. Namely, explain why the second ionization energy for sodium is higher than for magnesium.
5. Circle the atom with largest more negative electron affinity P
6.
Si
Al
In which of the following lists do the ions not appear in the correct order of increasing ionic radius?
a. Li+ < Na+ < K+
Al3+ < Mg2+ < Na+
b.
d. d. S2- < Cl- < K+
e.
Cl - < Br - < I-
c. Na+ < F- < O2-
7. Calculate the lattice energy for CaH2 in kJ/mole. The Ea for H (g) is -72.8 kJ/mol. The Ei1 for Ca (g) is 589.8 kJ/mol.
The Ei2 for Ca (g) is 1145 kJ/mol. The heat of sublimation for Ca (s) is 178.2 kJ/mol. The bond dissociation energy
for H2 is 435.9 kJ/mole. The net energy change for the formation of CaH2 from its elements is -186.2 kJ/mole.
2
SI Practice Exam 4
CHM 111 Summer 2013
SI Leader: Kristen Kelly
8. Which of the following pictures represents NaCl and MgO? Which has the larger lattice energy?
9. Draw at least two Lewis structures for the sulfite ion, SO32-. Identify the better structure by assessing formal charge. If
this structure exists in resonance draw possible resonance structures. Draw the resonance hybrid. Indicate the
hybridization (central atom) and shape of one resonance structure. State the bond angle associated with this shape.
10. Draw the following molecules and indicate the hybridization (each atom) and shape (central atom):
a. SiF62-
b. H2SO4
3