Leader:
Course:
Instructor:
Date:
Exam 4 Review
Supplemental Instruction
Iowa State University
Lilli Howard
Chem 177 (BC)
Dr. Irmi
11/14/13
End of Chapter 7
7.5
1. Electron affinity is the energy change accompanying the (addition/subtraction) of an
(proton/electron) to a (gaseous/metallic) atom.
2. In general, electron affinity becomes more (endothermic/exothermic) as you go from left
to right across a row.
7.8
3. Substances containing only nonmetals are (molecular/ionic) compounds.
4. Most nonmetal oxides are (basic/acidic)
5. What are the oxo-acids that correspond to these oxo-anions?
1. CO32H2CO3
2. PO43H3PO4
3. ClO
HClO
6. Most metal oxides are (basic/acidic).
7. There are two forms of oxygen, O2 and O3. Elements that can exist in two or more
different forms are called __allotropes_____________.
8. What is an example of an acidic non-metal oxide?
1. What would be the products of this oxo-acid in a dehydration reaction?
2. What is the conjugate base of this oxide?
H2SO3
SO2
HSO3
9. What are some examples of chalcogens? What are some characteristic properties?
increasing metal character as the atomic number increases
smaller members of the group show a greater tendency to form covalent bonds than the larger
members do
10. What are some examples of halogens? What are some characteristic properties?
Seven valence electrons (one short of a stable octet)
Highly reactive, especially with alkali metals and alkaline earth
1060 Hixson-Lied Student Success Center  515-294-6624  sistaff@iastate.edu  http://www.si.iastate.edu
Also know metals and non metals and noble gases
Chapter 12.7
11. A semiconductor has electrical conductivity between that of a(n)
___conductor___________ and a(n) _______insulator________.
12. We talked about two kinds of semi conductors. III-V and II-VI. What are examples of
each?
AlP
ZnSe
13. The conductivity of a semiconductor can be increased by doping it with a small amount
of impurity.
1. A dopant that adds an electron makes a __n___-type semiconductor.
2. A dopant that accepts electrons makes a __p____-type semiconductor.
14. What kind of conductor is silicon doped with boron?
P- type
→ LEDs Read page 491
Chapter 8
15. There are three basic types of bonds:
1. electron transfer: __ionic_____
2. electron pair sharing: _____covalent_________
3. electron band sharing: ____metallic__________
16. __Valence____ electrons of atoms interact to form bonds
17. What is the octet rule? When do we use it? What are some exceptions?
Atoms of low (<20) atomic number tend to combine in such a way that they each have eight
electrons in their valence shells, giving them the same electron configuration as a noble gas
18. Draw the Lewis Structures for the following molecules.
1. HOCl
2. NH4Cl
3. SiH4
4. BH45. H2CO
6. BI3
7. PF5
8. NO
1060 Hixson-Lied Student Success Center  515-294-6624  sistaff@iastate.edu  http://www.si.iastate.edu
19. HCN and HNC are both possible arrangements of the empirical formula HCN. Which is
more likely to exist? (Use formal charges to find the answer)
HCN: 0, 0, 0
HNC: 0. +1, -1
-HCN is most likely
20. Bond enthalpy is defined as the enthalpy change required to break a bond of a gaseous
substance. This value is always (positive/negative).
21. Calculate the bond enthalpy for the combustion of propane.
C-H
C-C
O=O
C=O
H-O
+413
+347
+498
+805
+464
CH3CH2CH3(g) + 5 O2 (g) → 3CO2(g) + 4H2O
(8 x +413) + 2(+347) + 5(+498) - (6 x -805) + (8 x -464) = - 2054 kJ mol-1
22. The measure of stability of a solid ionic substance is called its _lattice_energy___.
23. (Small/large) ion charges and (small/large) distances between oppositely charged ions
yield large lattice energies.
24. The best Lewis structure puts the negative formal charge on the atom with the most
_electronegative atom_____.
25. Draw all resonance structures for CO32-
1060 Hixson-Lied Student Success Center  515-294-6624  sistaff@iastate.edu  http://www.si.iastate.edu
26. metals with nonmetals: _______ionic______________________________
27. metals with metals: _______metallic______________________________
28.
29. nonmetals with nonmetals: _______covalent_______________________________
30. Electronegativity difference > 2 : ___ionic_____________________________
31. Electronegativity difference < 2 and average electronegativity large: ___polar covalent_
32. Electronegativity difference zero and average electronegativity large: non-polar covalent
33. Electronegativity difference small and average electronegativity small: _metallic__
34. What is a polar covalent bond? What is an example?
A covalent bond between two atoms where the electrons forming the bond are unequally
distributed
H20
CO3
35. Rank the following bonds in order from covalent to most ionic.
a) Na-Cl
b) Li-H
c) H-C
d) H-F
e) Rb-O
2.1
1.1
.4
1.9
2.7
Given the following electronegativity values:
Na = 0.9
Li = 1.0
Cl = 3.0
H = 2.1
Rb = 0.8
O = 3.5
F = 4.0
C = 2.5
C<B<D<A<E
1060 Hixson-Lied Student Success Center  515-294-6624  sistaff@iastate.edu  http://www.si.iastate.edu
Chapter 9
36. How many electrons occupy pi orbitals in CO2?
4
37. Write out the MO energy-level diagrams for N2, N2+, N2-. Find the bond order for each.
Which is the most stable?
38. Draw and name examples of the following electron domain geometries:
1. Linear
CO2
2. Trigonal Planar
BF3
3. Tetrahedral
CO4
4. Trigonal Bipyramidal
PF5
39. How many electron domains surround the central atom in a water molecule? Draw the
Lewis structure.
4
40. Do SO2 and SO3 possess dipole moments?
SO2 does. SO3 doesn't
1060 Hixson-Lied Student Success Center  515-294-6624  sistaff@iastate.edu  http://www.si.iastate.edu
41. For the following, draw the Lewis structure, state the total number of electron domains.
Predict the structure. Circle the polar molecules.
1. SF2
4- tetrahedral
2. SF4
5- triganol bipyramidol
3. SF6
6 – square pyramidol
1060 Hixson-Lied Student Success Center  515-294-6624  sistaff@iastate.edu  http://www.si.iastate.edu