AP Chemistry Atomic Structure and Bonding Test – Take Home
Name ___________________________________________________________
1. The table below shows the first three ionization energies for atoms of four elements from the second period of the periodic table. The elements are numbered randomly. Use the information in the table to answer the following questions. (3 pts. ea.)
Element 1
Element 2
Element 3
Element 4
First ionization energy kJ mol -1
899.5
1681.0
520.2
1402.3
Second ionization energy kJ mol -1
1757.1
3374.0
7298.1
2856.0
Third ionization energy kJ mol -1
14,848.7
6050.3
11,815.0
4578.0 a. Which element is most metallic in character? Explain your reasoning. b. Identify element 3. Explain your reasoning. c. Write the complete electron configuration for an atom of element 3. d. What is the expected oxidation state for the most common ion of element 1? e. What is the chemical symbol for element 1? f. A neutral atom of which of the four elements has the smallest radius? Explain you reasoning.

2. Answer the following questions related to arsenic and its compounds. a. Consider the two chemical species As and As 3. i. Write the electron configuration of each species. (4 pts.) ii. Explain why the radius of the As 3 ion is larger than the radius of the As atom. (2 pts.) iii. Which of the two species would be attracted to a magnetic field? Explain. (2 pts.) b. The As 3 ion is isoelectronic with the Kr atom. From which species, As 3 or Kr, is it easier to remove an electron? Explain. (2 pts.) c. Arsenic can react with chlorine to form AsCl
3
or AsCl
5
. Draw the complete Lewis electron dot diagram for each of these molecules. (4 pts.) d. On the basis of the Lewis electron dot diagrams you drew in part c, predict the following:
I. The geometric shape of each molecule. (2 pts.) ii. The hybridization of arsenic in each molecule. (2 pts.) iii. Predict whether each molecule is polar or nonpolar. (2 pts.)

3. Using the principles of atomic and molecular structure, answer the following questions. a. Write the equations for the first and second ionization of magnesium. (4 pts.) b. Account for the fact that the second ionization energy of magnesium is higher than the first ionization energy of magnesium. (3 pts.) c. Account for the fact that the first ionization energy of magnesium is higher than that of sodium. (3 pts.) d. Account for the fact that the second ionization energy of sodium is higher than the second ionization energy of magnesium. (3 pts.) e. Answer the following questions about the carbonate ion, CO
3
2. i. Draw the Lewis electron dot diagram for this polyatomic ion. (2 pts.) ii. In the carbonate ion, all of the bonds have the same length. Explain this observation.
(2 pts.) iii. How many sigma and pi bonds are in the carbonate ion? (2 pts.)

4. Nitrogen gas reacts with hydrogen gas to form ammonia. (5 pts. ea.)
N
2
+ 3 H
2
 2 NH
3 a. A 25.0 L sample of nitrogen gas at STP is placed in a reaction vessel containing 3.15 moles of
H
2(g)
. i. Identify the limiting reactant when the nitrogen and chlorine gases are combined.
Justify your answer with a calculation. ii. Calculate the total number of moles of NH
3
in the container after the limiting reactant has been totally consumed. b. The energy to break the N = N bond is 941 kJ mol -1 . Calculate the amount of energy, in joules, needed to break a single N
2
molecule. c. Calculate the longest wavelength of light, in meters, that can supply the energy per photon necessary to break apart the N
2
molecule.

5. Write the balanced net ionic equations and answer the questions for each of the following. (5 pts. ea.) a. solid ammonium nitrate decomposes as it is heated. i. balanced equation: ii. Predict the algebraic sign of ΔS for this reaction. Explain your reasoning. b. A small piece of potassium metal is placed in a beaker of distilled water. i. Balanced equation: ii. As the reaction proceeds, the resulting solution becomes basic. Explain this observation. c. Bromine, an oxidizing agent, is added to a solution of potassium iodide. i. Balanced equation: iii. What is the oxidation number of bromine before AND after the reaction occurs? d. Solid calcium hydroxide is added to a solution of chloric acid. i. Balanced equation: ii. How many moles of calcium hydroxide would react completely with 200. mL of 0.50 M chloric acid?