Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____ 1. The 3p atomic orbital has the shape of a. a sphere b. a torus c. a dumb-bell d. two perpendicular dumb-bells e. an egg
____ 2. Which of the following elements would have the lowest first ionization energy? a. sodium d. chlorine b. aluminum c. nitrogen e. argon
____ 3. Rutherford's gold foil experiment showed that the atom is mostly empty space because a. some of the alpha particles were reflected right back b. some of the alpha particles were deflected c. most of the alpha particles went straight through the foil d. all of the alpha particles went straight through the foil e. all of the alpha particles were deflected
____ 4. What was Planck's contribution to the quantum mechanical model of the atom? a. the uncertainty principle b. the concept of quanta of energy c. the idea that every mass has a wave with which it is associated d. the wave equation e. a relationship between energy and mass
____ 5. What did Schrodinger contribute to the quantum mechanical model of the atom? a. the uncertainty principle b. concept of quanta of energy c. the idea that every mass has a wave with which it is associated d. the wave equation e. a relationship between energy and mass
____ 6. "A region of space in which there is a high probability of finding an electron" is the definition of a. orbital d. photon b. absorption spectrum c. quantum e. dipole
____ 7. Which of the following is the electron configuration for the valence shell of oxygen? a. d. b. e. c.
1

____ 8. Which of the following is the electron configuration for magnesium? a. 1s 2 2s 2 2p 8 d. 1s 3 2s 3 2p 3 3s 2 b. 1s 3 2s 3 2p 4 3s 2 c. 1s 2 2s 2 2p 7 3s 1 e. 1s 2 2s 2 2p 6 3s 2
____ 9. How was Bohr able to discover the energies of each energy level in the hydrogen atom? a. using the fact that most alpha particles went straight through the gold foil b. using the fact that some alpha particles were deflected by the gold foil c. using the line spectrum of hydrogen when it is excited d. using the fact that atoms are electrically neutral e. none of the above
____ 10. Which of the following is always true of all electrons in the same principal energy level. a. they possess the same energy d. all of the above b. they have opposite spins c. they are in identical orbitals e. none of the above
____ 11. Why do halogens have high electron affinities? a. their electron configurations are close to noble gases b. they have low electronegativities c. they have high ionization energies d. all of the above e. none of the above
____ 12. Why is phosphorus able to have a valence of 5+? a. it is in group 5 b. it has five valence electrons c. its most easily removed electron is in a p orbital d. it has empty d orbitals e. none of the above
____ 13. Why do non-metals have high electronegativities? a. they are very small atoms and thus have a stronger hold on their electrons b. they are on the left side of the periodic table c. they contain many protons therefore they have a stronger hold on their electrons d. they can easily become iso-electronic with noble gases by accepting electrons e. none of the above
____ 14. Which element is the most electronegative? a. helium b. fluorine c. francium d. hydrogen e. sodium
____ 15. Which is true of all p-block elements? a. they are all metals b. they have relatively low electron affinities c. they are all non-metals d. they have relatively high electronegativities e. none of the above
____ 16. Which atoms could have the valence electron configuration shown below?



 s p a. N 3b. O 2d. Cl 1e. all of the above
2

c. Ar
____ 17. Which of the following is the electron configuration for a halogen? a. 1s 2 2s 2 2p 4 d. 1s 2 2s 2 b. 1s 2 2s 2 2p 6 c. 1s 2 2s 2 2p 5
3s 1 e. 1s 2 2s 2 2p 6
____ 18. Which technology uses superconductors? a. MRI b. spectrophotometer c. X-ray d. laser e. none of the above
____ 19. Which technology demonstrates the principles of quantum mechanics? a. laser d. MRI b. spectrophotometer c. X-ray machine e. all of the above
____ 20. In which of the following situations is a spectrophotometer a useful instrument? a. producing new substances d. microsurgery b. producing high energy photons c. detecting trace amounts of substances e. all of the above
____ 21. What is the definition of a superconductor? a. contains iron and conducts electricity very well b. contains helium and conducts electricity c. conducts electricity only at low temperatures d. conducts electricity at room temperature e. conducts electricity with a resistance near zero
____ 22. Polar covalent bonds occur between a. atoms which both have equally high electronegativities b. atoms which have high but unequal electronegativities c. atoms which both have equally low electronegativities d. atoms which both have equally low ionization energies e. atoms which have low but unequal ionization energies
____ 23. According to VSEPR theory, molecules adjust their shapes to keep which of the following as far apart as possible? a. pairs of valence electrons b. inner shell electrons c. bonding pairs of electrons d. mobile electrons e. lone pairs of electrons
____ 24. What causes high surface tension in water? a. the high boiling point of water b. the bent shape of the molecule c. hydrogen bonding d. the low density of ice e. none of the above
____ 25. What type of substance is potassium chloride, KCl? a. ionic d. metallic b. molecular c. covalent network e. none of the above
____ 26. Which gaseous molecule is non polar? a. ozone, O
3 b. HCl c. H
2
O d. NH e. CH
3
4
____ 27. How would Dr. Richard Bader probably describe a double bond? a. an electron density that is twice as high as a single bond b. a higher electron density than a single bond
3

4 c. four electrons shared between two atoms d. all of the above e. none of the above
____ 28. What is the shape of ammonium, NH
4
1+ ? a. linear b. trigonal planar c. tetrahedral
____ 29. What is the shape of the nitrate ion, NO
3
1? a. linear b. trigonal planar c. tetrahedral d. octahedral e. trigonal pyramidal d. octahedral e. trigonal pyramidal
____ 30. "A partial positive charge at one end of a molecule combined with a partial negative charge at the other end of a molecule" describes... a. an orbital b. an absorption spectrum c. a quantum d. a photon e. a dipole
Short Answer
31. Draw and write the electron configuration for calcium.
32. According to Bohr, why do electrons travel in specific energy levels around the nucleus?
33. Distinguish between the terms "photon" and "quantum".
34. Distinguish between single and double bonds with respect to the bonding orbitals.
35. How would you determine the potential energy of the last electron in sodium?
36. Draw the electron configuration for Scandium, Sc .
37. Draw the electron configuration for the chloride, Cl 1, ion.
38. What is meant by the term "orbital"?
39. What do chemists use Schrodinger's equation to do?
40. How has our understanding of quantum mechanics helped in the medical field?
41. Explain why CH
3
F is a polar molecule while CF
4
is not.
42. Explain how VSEPR theory explains the shape of a central atom surrounded by two unbonded pairs of electrons and two other atoms.
43. What would be the shape of NO
3
-1 ? Explain your reasoning.
44. Is ammonia a polar molecule? Explain your answer using a diagram.
45. Describe and name the type of solid that is formed by calcium. Explain your answer.
46. Explain the term "sea of electrons" with respect to metallic bonding.
47. What kinds of chemical bonds or attractive forces must be broken in order to melt diamond?
48. What are bond angles?
49. Why is the bond angle in water, H
2
O, less than the bond angles in ammonia, NH
3
?

50. Why is the bond angle in carbon dioxide, CO
2
, 180 o ?
51. Why does hydrogen bonding occur in water, H
2
O, but not hydrogen sulfide, H
2
S?
52. Why do metals conduct heat?
53. Explain why ionic compounds are brittle.
54. Why do metals conduct electricity?
Essay
55. Explain water's properties using what you know about its inter- and intramolecular forces.
56. Explain VSEPR theory in your own words. Use examples.
57. Describe, in your own words, two allotropes of carbon. Include a comparison of physical and chemical properties.
5

6
MULTIPLE CHOICE
1. ANS: C
2. ANS: A
3. ANS: C
4. ANS: B
5. ANS: D
6. ANS: A
7. ANS: B
8. ANS: E
9. ANS: C
10. ANS: E
11. ANS: A
12. ANS: D
13. ANS: D
REF: K/U
REF: K/U
REF: K/U
REF: K/U
REF: K/U
REF: C
REF: C
REF: C
REF: K/U
REF: K/U
REF: K/U
REF: K/U
REF: K/U
OBJ: 3.5
OBJ: 3.6
OBJ: 3.1
OBJ: 3.3
OBJ: 3.7
OBJ: 3.5
OBJ: 3.6
OBJ: 3.6
OBJ: 3.4
OBJ: 3.6
OBJ: 3.6
OBJ: 3.6
OBJ: 3.6
LOC: SP1.02
LOC: SP1.03
LOC: SP1.01
LOC: SP1.02
LOC: SP1.02
LOC: SP2.01
LOC: SP2.02
LOC: SP2.02
LOC: SP1.01
LOC: SP1.02
LOC: SP1.03
LOC: SP1.03
LOC: SP1.03
14. ANS: B
15. ANS: D
16. ANS: E
17. ANS: C
18. ANS: A
19. ANS: E
20. ANS: C
REF: K/U
REF: K/U
REF: I
REF: I
REF: MC
REF: MC
REF: MC
OBJ: 3.6
OBJ: 3.6
OBJ: 3.6
OBJ: 3.6
OBJ: 3.8
OBJ: 3.8
OBJ: 3.8
LOC: SP1.03
LOC: SP1.03
LOC: SP2.02
LOC: SP2.02
LOC: SP3.01
LOC: SP3.01
LOC: SP3.01
21. ANS: E REF: MC OBJ: 3.7 LOC: SP3.02
22. ANS: B
Atoms with unequal electronegativities will not share electrons equally, therefore one end of the bond ends up with a partial positive charge and the other ends up with a partial negative charge. Atoms with low electronegativities are metals, which do not bond covalently with each other.
REF: C OBJ: 4.4 LOC: SP2.04
23. ANS: A
24. ANS: C
25. ANS: A
26. ANS: E
27. ANS: B
28. ANS: C
29. ANS: B
30. ANS: E
REF: I
REF: K/U
REF: I
REF: I
REF: MC
REF: I
REF: I
REF: C
OBJ: 4.3
OBJ: 4.5
OBJ: 4.6
OBJ: 4.4
OBJ: 4.3
OBJ: 4.3
OBJ: 4.3
OBJ: 4.4
LOC: SP2.03
LOC: SP1.04
LOC: SP2.05
LOC: SP2.04
LOC: SP3.03
LOC: SP2.03
LOC: SP2.03
LOC: SP2.01
SHORT ANSWER
31. ANS:

REF: C OBJ: 3.6 LOC: SP2.02
32. ANS:
Electrons may only possess specific amounts of energy thus they can only exist at specific distances from the nucleus.
REF: K/U OBJ: 3.4 LOC: SP1.01
33. ANS:
- A "quantum" is the concept of a packet of energy.
- A "photon" is a particle of light.
REF: C OBJ: 3.3 LOC: SP2.01
34. ANS:
- In a single bond, there is direct overlap of two orbitals.
- In a double bond, two orbitals directly overlap and two others overlap laterally.
REF: C OBJ: 4.2 LOC: SP2.01
35. ANS:
Determine the amount of energy it takes to remove that electron, then negate the number.
REF: K/U OBJ: 3.4 LOC: SP1.01
36. ANS:


3d

4s


3s
3p

 2p
2s

1s
7

REF: C
37. ANS:

3s

2s

1s
REF: I

3p

2p
OBJ: 3.6 LOC: SP2.02
OBJ: 3.6 LOC: SP2.02
38. ANS: volume of space in which there is a high probability of finding an electron
REF: C OBJ: 3.5 LOC: SP2.01
39. ANS: to graph the probability of finding an electron in three dimensional space around a nucleus
REF: K/U OBJ: 3.7 LOC: SP1.02
40. ANS:
- laser used in surgery
- rays, CT scans, MRIs used for diagnostics
REF: MC OBJ: 3.8 LOC: SP3.01
41. ANS:
Both species have a tetrahedral structure. This shape is symmetrical in all directions. Therefore, even though the CF
4
molecule contains four polar bonds, there is no positive end and negative end; therefore the molecule itself is not polar. However, the CH
3
F molecule contains only one C-F bond. The F draws electrons from the rest of the molecule as well, forming a partial negative charge at its end, and leaving the hydrogens with partial positive bonds.
REF: I OBJ: 4.4 LOC: SP2.04
42. ANS:
The two bonded pairs and two unbonded pairs of electrons around the central atom and then spread out in space so that they can be as far apart as possible. Thus, they form a tetrahedral shape. The shape of water(H-
O-H) ends up being bent. because the unbonded pairs of electrons are invisible.
REF: K/U OBJ: 4.3 LOC: SP1.05
43. ANS:
It would be a trigonal planar molecule, because nitrogen would have three oxygen atoms and no unbonded pairs of electrons around it. This configuration would get the bonded electrons as far apart as possible.
REF: I OBJ: 4.3 LOC: SP2.03
44. ANS:
Ammonia would be polar because it has a lone pair that pushes the hydrogens down, forming an asymmetric molecule. Also, nitrogen is highly electronegative, so each N-H bond is polar.
8

9
REF: I OBJ: 4.4 LOC: SP2.04
45. ANS:
Calcium forms a metallic solid. It is essentially a lattice made of positively charged calcium ions surrounded by delocalized electrons, which travel around and between each of the metal ions.
REF: I OBJ: 4.6 LOC: SP2.05
46. ANS:
Metals have low electron affinities. As a result, the electrons in metals are delocalized so that metals consist of positive ions are surrounded by the delocalized electrons, resulting in the term the "electron sea".
REF: K/U OBJ: 4.6 LOC: SP1.04
47. ANS: covalent bonds
REF: K/U OBJ: 4.6 LOC: SP1.04
48. ANS:
Bond angles are the angles formed by the bonds between any three adjacent atoms in a molecule.
REF: K/U OBJ: 4.3 LOC: SP1.05
49. ANS:
The oxygen in water is surrounded by two hydrogen atoms and two lone pairs of electrons. The nitrogen in ammonia is surrounded by three hydrogen atoms and one lone pair of electrons. Since each central atom is surrounded by four things, each molecule's shape is based on the tetrahedron with bond angles of 109 o .
However, oxygen's two lone pairs take up more room than nitrogen's one. This means that oxygen's lone pairs will push down on the hydrogens more, and thus produce a smaller angle.
REF: K/U OBJ: 4.3 LOC: SP1.05
50. ANS:
Carbon dioxide contains a carbon double bonded to two oxygen atoms. There are no lone pairs around the central atom; therefore the atom is linear, to keep the bonded electrons as far apart as possible.
REF: K/U OBJ: 4.3 LOC: SP1.05
51. ANS:
The electronegativity difference is not big enough between hydrogen and sulfur to make the H-S bond polar enough to make H as positive as it is when bonded to O.
REF: I OBJ: 4.4 LOC: SP2.04
52. ANS:
The delocalized electrons are free to move, therefore they vibrate more vigorously and can thus conduct more heat.
REF: I OBJ: 4.6 LOC: SP2.05
53. ANS:

10
Ions are arranged in a lattice so that each positive ion is surrounded by negative ions and vice versa. If two layers in this lattice are shifted, two like charged ions come close to each other and repel, thus breaking apart the lattice.
REF: I OBJ: 4.6 LOC: SP2.05
54. ANS:
The delocalized electrons are free to move from one place to another, thus forming an electric current.
REF: I OBJ: 4.6 LOC: SP2.05
ESSAY
55. ANS:
Water is a small covalent compound that is highly polar. It does not conduct electricity as it is not ionic and there are no delocalized electrons. The molecule is polar because the oxygen has two lone pairs of electrons.
Thus, the shape is based on a tetrahedron and the molecule is bent. Since oxygen is so electronegative, the electrons spend more time with it than the hydrogens, and the molecule ends up being polar. The hydrogens- each with partial positive charges- are then attracted to the partially negative oxygens on other water molecules. This causes cohesion between water molecules, which means that is more difficult to change it to a gas. Thus, water has an extremely high boiling point compared to other molecules like it. Also, since it is able to absorb more energy before it changes state, it has a high heat capacity and is an excellent insulator. Its polarity allows it to cling to objects easily.
REF: K/U OBJ: 4.5 LOC: SP1.04
56. ANS:
- Electrons repel; therefore, they will attempt to stay as far apart as possible in a molecule. To do this, bond angles must be maximized.
- Lone pairs take up more room than bonded pairs and they repel more.
- In methane, the carbon is surrounded by four hydrogen atoms. If the bonded pairs of electrons are to stay as far apart as possible in three-dimensions, they will be 109 o apart. This produces a characteristic tetrahedral shape. If the molecule is like ammonia, though, with a lone pair and three atoms bonded to the central atom, the shape is still based on the tetrahedron, but, since the lone pair takes up more room, the bond angles for the N-H's will be smaller than 109 o . However, the shape is named by the atoms only, therefore the shape would be trigonal pyramid. For five atoms surrounding a central atom, our choice in angles is limited by the orientation of orbitals in space. Thus, the angles are 90 o and 120 o instead of having all of the angles equal.
REF: K/U OBJ: 4.3 LOC: SP1.05
57. ANS:
Graphite and diamond are both allotropes of carbon. Graphite is a solid with a high melting point. It is made up of layers of carbon atoms that bonded to three other carbon atoms (bond angles of 120 o ). Layers are held together by dispersion forces. They are easily rubbed off, thus it is used in pencils and as a lubricant. Graphite conducts electricity because each carbon atom is surrounded by three covalent bonds and one delocalized electron that is free to move. Diamond is also a solid, but it does not conduct electricity because each carbon is surrounded, tetrahedrally, by four other carbon atoms. No delocalized electrons are present. This array is extremely hard. Graphite is black, since the delocalized electrons are available to absorb light and diamond is colourless. In spite of the difference in physical properties, the chemical properties are identical.
OBJ: 4.6 LOC: SP2.05 REF: C