Write a lewis structure for each molecule a b c hi d

51. Write a Lewis structure for each molecule:
a. b. c. HI d.
52. Write a Lewis structure for each molecule:
a. b. HBr c. d. CCl
4
SBr
2
NF
3
CH
4
SCl
2
PH
3
NH
4
NH
2
NH
3
.
Lattice Energy (kJ/mol)
MgO –3795
CaO –3414
SrO –3217
- 3029 kJ > mol.
- 744 kJ > mol,
- 671 kJ > mol.
- 617 kJ > mol,
Metal Oxide Lattice Energy (kJ/mol)
MgO –3795
CaO –3414
SrO –3217
BaO –3029
energy to form the ion than the amount of energy released
upon formation of
11. What is the Born–Haber cycle? List each of the steps in the
cycle and show how the cycle is used to calculate lattice energy.
12. How does lattice energy relate to ionic radii? To ion charge?
13. How does the ionic bonding model explain the relatively high
melting points of ionic compounds?
14. How does the ionic bonding model explain the nonconductivity
of ionic solids, and at the same time the conductivity of ionic
solutions?
15. Within a covalent Lewis structure, what is the difference be-
tween lone pair and bonding pair electrons?
16. In what ways are double and triple covalent bonds different
from single covalent bonds?
17. How does the Lewis model for covalent bonding account for
why certain combinations of atoms are stable while others
are not?
18. How does the Lewis model for covalent bonding account for the
relatively low melting and boiling points of molecular com-
pounds (compared to ionic compounds)?
19. What is electronegativity? What are the periodic trends in elec-
tronegativity?
20. Explain the difference between a pure covalent bond, a polar
covalent bond, and an ionic bond.
21. Explain what is meant by the percent ionic character of a bond.
Do any bonds have 100% ionic character?
Cl
-
?
Na
+
22. What is a dipole moment?
23. What is the magnitude of the dipole moment formed by separat-
ing a proton and an electron by 100 pm? 200 pm?
24. What is the basic procedure for writing a covalent Lewis
structure?
25. How do you determine the number of electrons that go into the
Lewis structure of a molecule? A polyatomic ion?
26. What are resonance structures? What is a resonance hybrid?
27. Do resonance structures always contribute equally to the overall
structure of a molecule? Explain.
28. What is formal charge? How is formal charge calculated? How
is it helpful?
29. Why does the octet rule have exceptions? Give the three major
categories of exceptions and an example of each.
30. What elements can have expanded octets? What elements
should never have expanded octets?
31. What is bond energy? How can average bond energies be used
to calculate enthalpies of reaction?
32. Explain the difference between endothermic reactions and
exothermic reactions with respect to the bond energies of the
bonds broken and formed.
33. What is the electron sea model for bonding in metals?
34. How does the electron sea model explain the conductivity of
metals? The malleability and ductility of metals?
TROMC09_358-397hr.qxd 13-11-2009 14:58 Page 394

Exercises
395