Unit 3

There are three topics in Unit 3.  The first one, oxidation-reduction reactions, is a fairly short topic.  It’s important to the course though as it is a necessary tool to look at two major topics coming up: coordination chemistry (in this unit) and electrochemistry (in Unit 4).

In the next topic, transition metals and coordination chemistry, you will get a closer look at the elements in the middle of the periodic table, where the d orbitals are partially filled (first semester classes tend to focus most of their time on the representative elements at either end of the periodic table.  These elements (the transition metals) form a large variety of ionic compounds known as coordination compounds, and the bulk of the topic is devoted to these compounds and their properties.

The unit will end with the topic of chemical thermodynamics.  You have likely studied the first half of thermodynamics by studying the concepts of energy in chemical processes (thermochemistry) and topics like exothermic and endothermic reactions, specific heat, etc.  We will pick up there and continue with the second half, which includes the concepts of entropy, direction of chemical reactions, whether reactions occur spontaneously, and connections to equilibrium.  A review of necessary concepts you learned in thermochemistry will be included.

Unit 3 Objectives

Oxidation-Reduction Reactions

1. Identify oxidation-reduction (redox) reactions
2. Define the terms oxidation and reduction in terms of loss or gain of electrons and impact on oxidation state
3. Identify which element is oxidized and which element is reduced in a redox reaction
4. Assign oxidation states to the elements in a compound or ion.
5. Predict the products for the single replacement reaction of a metal with an acid, water, or salt and use the activity series to predict whether a reaction will occur
6. Identify oxidizing and reducing agents in redox reactions.
7. Balance oxidation-reduction reactions using the half-reaction method in both acidic and basic solutions.

Transition Metals and Coordination Chemistry

1.    Define, explain and/or give an example of the following:

1. • central ion (transition metal ion)
   • metal complexes
   • complex ion
   • ligand
   • coordination sphere
   • coordination number
   • geometry
2. Describe the structure of coordination compounds including: the central atom, ligands, metal complex, coordination number, geometry, and oxidation number.
3. Write electron configurations for transition metal atoms and metal ions.
4. Define isomerism and give an example.
5. Distinguish between structural isomerism and stereoisomerism. (note: Optical isomerism is NOT covered)
6. Identify and draw structures for the following types of isomerism: structural, stereoisomers, coordination sphere, linkage and geometric.
7. State the basic assumptions of the crystal field model.
8. Explain how the electrostatic interaction between the ligand and the metal’s d-orbitals in an octahedral field results in the splitting of the energy levels.
9. Explain the splitting of the energy levels in a tetrahedral complex and the reason for the smaller crystal field splitting compared to the octahedral complexes.
10. Draw d-orbital splitting diagrams for octahedral and tetrahedral complexes.
11. Distinguish between high and low spin complexes and strong and weak field octahedral complexes.
12. Explain the origin of color in complexes using d-orbital splitting.
13. Explain the significance of the spectrochemical series.
14. Given a spectrochemical series, predict whether a complex ion is more likely to have weak or strong crystal field splitting.
15. Explain how the colors of substances are related to their absorption and reflection of incident light.
16. Know the characteristic colors of the following common transition metal ions: Fe³⁺, Ni²⁺, Cu⁺, Cu²⁺, Co²⁺, Mn⁷⁺, Mn⁴⁺
17. Explain how crystal field theory can be used to predict whether a complex is diamagnetic or paramagnetic.
18. Predict the number of unpaired electrons in a high and low spin octahedral complex and determine if that complex is diamagnetic or paramagnetic.

Chemical Thermodynamics

1. Define or explain and give an example of each of the following terms.
   • spontaneous process
   • state function (see pg 167)
   • system
   • surroundings
   • reversible and irreversible processes
2. Explain how entropy is related to randomness or disorder, positional probability, and the number of microstates available to the system.
3. Predict whether a process is spontaneous.
4. Predict the relative number of microstates available to a system under varying conditions, or using your understanding of the relative number of microstates available to systems predict whether entropy of a system increases or decreases.
5. Predict the sign of the entropy change for a given process, phase change, or chemical reaction.
6. Calculate ΔS° for a chemical reaction using the tabulated S° values of the reactants and products and a balanced equation.
7. State and explain the second law of thermodynamics in terms of entropy. Understand the relationship of the entropy change in the system, surroundings, and universe to the second law.
8. Explain the temperature dependence of entropy and predict how spontaneity can be affected by increasing or decreasing temperature.
9. Given any two of the following variables, ΔS, ΔH or T calculate the third variable.
10. Define free energy and relate it to spontaneity.
11. Given ΔH, ΔS, and T, calculate the change in Gibbs Free Energy and then predict whether a process will be spontaneous.
12. Define and write the equation for the standard free energy of formation, ΔG_f° of a substance.
13. Calculate ΔG°, ΔH° and ΔS° for a reaction from tabulated data.
14. Given temperature and any two of the following variables, ΔS, ΔH or ΔG,  calculate the third variable
15. Explain how ΔG changes with a change in the concentration or partial pressure of reactants or products.
16. Calculate ΔG given the concentration or partial pressures of reactants and products.
17. Explain equilibrium in terms of minimum free energy and show how the value of K is related to free energy.
18. Calculate ΔG° from K and vice-versa.
19. Predict how ΔG° will change with temperature given ΔH°  and ΔS°.
20. Explain the relationship between the maximum work obtainable and the free energy change.
21. Explain the relationship between kinetics and thermodynamics.

 

 

Unit 3 Topics

Study these in order:

• Oxidation-Reduction
  • Bruce’s Notes – Oxidation-Reduction
  • Oxidation-Reduction – Suggested reading assignment and guide
• Transition Metals and Coordination Chemistry
  • Bruce’s Notes -Transition Metals and Coordination Chemistry
  • Transition Metals and Coordination Chemistry- Suggested reading assignment and guide
• Chemical Thermodynamics
  • Bruce’s Notes – Chemical Thermodynamics
  • Chemical Thermodynamics – Suggested reading assignment and guide
• Unit 3 – additional study resources
• Quiz 4

Unit 3 Online Homework

Link to the Unit 3 Online Homework Assignments