Exam 2 Practice Problems
Energy
1. An electron has an n value of 3. What are the possible l values? What are the possible
ml values?
2. Below is the electron energy diagram for hydrogen in the ground state. Draw the electron
energy diagram of helium in the ground state relative to that of hydrogen shown below.
1s
3. In lecture we discussed how the Bohr equation could be used for any “one-electron
system.”
a. What is meant by a one-electron system?
b. List three one-electron systems.
+
c. What is the energy of an electron in n4 of He ?
+
d. What is the energy of an electron in n of He ?
+
e. How much energy is needed to remove an electron from a He ion if the electron is in
n 4?
f. What is the frequency and wavelength of light describes in part e?
+
4. Write the electron configuration for F , Ne, and Na .
5. Rank fluoride, neon, and sodium ion in terms of size.
6. Write a chemical equation with a change in energy equal to IE2 for a nitrogen atom.
7. Write a chemical equation with a change in energy equal to EA2 for a nitrogen atom.
8. Which element in row two of the periodic table has the following ionization energies
(listed on kJ)?
∞
IE → 1
2080
10.
11.
12.
13.
14.
2
3950
3
6120
4
9370
5
6
7
8
9
12180 15240 20000 23070 115380
What are the four quantum numbers and what do they indicate?
Write out the full length and condensed electron configuration for Na, S, Mo, Ne, and Ce.
How many valence electrons do each of the elements in the previous problem have?
What is the molecular geometry of I3 ?
What is the indicated bond angle in the following molecule?
O
C
H
H
-
15. Which of the following molecules have the same number of valence electrons as NO2 ?
(there are no misprints in this question)
a. CO2
b. NO2
c. O3
d. CO3
e. CO2
16. What is the formal charge of nitrogen in the following Lewis dot structure?
-
O
N
O
O
17. Draw the Lewis dot structure for IF5.
18. Draw the Lewis structure for XeO2F2.
19. There are three possible resonance structures for N2O. Draw all three and determine
which is the most reasonable.
20. Draw a Lewis dot structure AND perspective drawing for SF6.
221. Which of the following are polar molecules? (CH2O, CH4, H2, CH3Cl, CO2, CO3 , CH2Cl2)
True/False
1. BF3 has a tetrahedral molecular geometry.
2. The molecular geometry and electronic geometry of nitrate are the same.
3. If we compare two molecules (NH3 and NF3) we would predict that the lone pair of
nitrogen would be closer to the nitrogen in NH3 compared with NF3.
4. The low boiling point of molecular nitrogen (N2) can be attributed to the low intermolecular
forces.
5. A molecule with the formula AX3E will have the same molecular and electronic geometry.
6. For a molecule with AX4E the lone pair will occupy an equatorial position.
7. The H – N – H bond angle in NH3 is 120°.