Chem 161 Ready for class? Chemical Bonding
1. For each compound given here, write what type of compound it is (molecular or ionic or acid).
(a) NH4Cl (b) AlH3 (c) O2 (d) CH4 (e) NH3 (f) H2O (g) PCl5
(h) SF4 (I) ClF3 (j) XeF2 (k) SF6 (l) BrF5 (m) XeF4 (o) CS2 (p) CH2Cl2
2. Write a chemical equation that goes with Lattice energy of CaCl2(s).
3. Draw the Lewis Dot structure of ..
(a) Na
(b) Cl
(c) O-2
(d) Mg+2
4. What is the relationship between bond strength and bond energy?
5. Nitrogen and hydrogen combine to form ammonia in the Haber process. Calculate (in kJ) the
standard enthalpy change H° for the reaction written below, using the bond energies given.
N2(g) + 3H2(g)  2NH3(g)
Bond:
Bond energy (kJ/mol):
NN
945
H–H
432
N–H
391
6. Acetone can be easily converted to isopropyl alcohol by addition of hydrogen to the carbon–oxygen
double bond. Calculate the enthalpy of reaction using the bond energies given.
Bond:
Bond energy (kJ/mol):
C=O
745
H–H
436
C–H
414
O–H
464
C–C
347
C–O
351
7. Define electronegativity.
8. Select the most polar bond amongst the following.
A) C–O B) Si–F C) Cl–F D) C–F E) C–I
9. Based on electronegativity trends in the periodic table, predict which of the
following compounds will have the greatest % ionic character in its bonds.
A) H2O B) LiI C) CaO D) RbF E) HCl
10. a) For each reaction given here, give at least one NAME for the energy. For example, the first one
will be called ‘heat of sublimation”
Mg(s) → Mg(g)
2+
ΔH° = 148 kJ
-
‘heat of sublimation”
Mg(g) → Mg (g) + 2e
ΔH° = 2186 kJ
?
S8(s) → 8S(g)
ΔH° = 2232 kJ
?
S(g) + 2e → S (g)
ΔH° = 450 kJ
?
8Mg(s) + S8(s) → 8MgS(s)
ΔH°= -2744 kJ
?
-
2-
b) What is the NAME for the energy associated with Mg2+(g) + S2-(g) → MgS(s) ?
c) Using Hess’s Law with equations given in (a), calculate the enthalpy change for Mg2+(g) + S2-(g) →
MgS(s) .
11. What is the relationship between (directly, inversely, not related?) …
a) Effective nuclear charge and atomic size
b) Energy and n
c) Stability and n
d) Effective nuclear charge and shielding
e) Ionization energy and atomic size
f) Number of electrons and size
g) Number of protons and size
h) Bond length and bond energy
i) Bond strength and bond energy
j) Bond length and bond order