This episode will now discuss the content of the AP Chemistry curriculum by describing the nine units outlined in the CED and their connections.
This episode will now discuss the content of the AP Chemistry curriculum by describing the nine units outlined in the CED and their connections. Unit 1 starts with the foundation of atomic structure and properties (1:43). In Unit 2, building on the foundation, students will learn about molecular and ionic compound structure and properties (2:27). Unit 3 then focuses on the intermolecular forces and properties (3:03), which are part of physical changes. In Unit 4 students will learn about chemical changes while being introduced to chemical reactions and stoichiometry (3:52). Unit 5 takes a closer look at the rate of a reaction and the which factors influence it (4:33). In Unit 6 the focus shifts towards the big idea of energy when talking about thermodynamics (5:15). Unit 7 lays the foundation for units 8 and 9, since it discusses chemical equilibrium (5:37). Unit 8 is an application of chemical equilibrium using acid-base chemistry (6:25). Unit 9, applications of thermodynamics has especially strong ties to unit 6 and 7 (7:12).
Question of the day: Which unit is most heavily weighted on the exam? (8:20)
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Hi and welcome to the APsolute Recap: Chemistry Edition. Today’s episode will recap an overview of the exam content
Let’s Zoom out:
In the last two episodes, we’ve talked about the exam itself and the big ideas and science practices. But what content do you need to know by May?
The exam is organized into nine units and they each have differential weighting - some units will therefore be longer and some will be a bit shorter. But what is a unit? And how does that differ from a chapter? Each unit on the exam will likely encompass multiple chapters from whatever textbook you are using. Even if your textbook says “AP Edition” it might have more information than you need to know and be organized in a different sequence from your teacher or the CED. And that’s okay! You can see the content taught as a state function - a term you will hear a lot throughout the school year. A state function is a value that only depends on its final and initial value - and not on the path how it got there. In our case: The only thing that matters is that you get through the entire content, it doesn’t matter in which order!
Each of these units is going to focus on the four big ideas which we covered in our last episode. Remember, the big ideas are scale, proportion, and quantity, structure and properties, transformation and energy.
Let's zoom in.
What are each unit’s title, the themes covered, the connected content, and what’s excluded from the exam?
Unit 1 - Atomic Structure and Properties. We are starting all the way at the beginning. This first unit lays the foundation of the course by focusing on atomic theory, periodic trends, electron configuration and an introduction to chemical quantities. To understand atomic structure, you might come across quantum numbers. They are nice to have met, but you do not have to be able to assign quantum numbers to electrons in subshells. One central aspect of this unit is Coulomb's Law. Understanding it will really help you build scientific arguments and explanations. This is a great unit to start with, because some of the content should already be familiar from your first year chemistry class and many of the concepts show up again on a deeper level further down the road.
Unit 2 - Molecular and Ionic Compound Structure and Properties is, you guessed it right, all about the big idea structure and properties. Since we know about Atomic Structure from Unit 1, we can learn about how atoms form chemical bonds and the properties of the resulting compounds. Within the unit you’ll hear about ionic, covalent and metallic bonding and you will take a closer look at the covalent bonds when talking about Lewis Diagrams and VSEPR theory. There will also be a brief introduction to bond hybridization with sigma and pi bonds. The structure will then be connected with the properties you can observe on a macroscopic level.
Unit 3 is a BIG one: Intermolecular Forces and Properties. In unit 2 we will have learned about INTRAmolecular forces. Unit 3 now focuses on INTERmolecular forces - the forces between molecules. This unit is actually about physical changes! You will be learning about the arrangement and motion of particles and relate the particle level to macroscopic observations you can make within solids, liquids and gases. A special focus will be on solution chemistry with liquids. You might see something in your textbook about colligative properties - like why salt lowers the freezing point - but this is not part of the AP Chemistry exam. Intermolecular forces itself will be a topic that will help you develop your scientific explanations and arguments making them especially important for the FRQ section!
Unit 4 is all about chemical reactions. We are finally at transformations! In this unit you will be introduced to chemical reactions by looking at types of equations, representation of reactions and stoichiometry. You will also be introduced to different types of chemical reactions, like acid-base and oxidation-reduction aka redox reactions. These will make a “comeback” in Units 8 and 9, respectively. When learning about chemical reactions and the signs of chemical reactions, you will hear about the formation of a precipitate, which is a compound insoluble in the solvent. You will not have to memorize solubility rules for the exam, which means you won’t have to know which compounds are soluble or insoluble.
In Unit 5 we will be introduced to Kinetics, which is the part of chemistry that looks at how fast a reaction is happening and which factors influence the rate of reaction. You will be learning what reaction rates are, how rates can be measured and how the rate and the concentration relate to one another. You will be using the collision model to explain macroscopic observations on a particulate scale, discuss energy profiles and the effect of catalysts. Before kinetics you usually looked at chemical reactions only in terms of reactants and products and not so much into what occurs during the transformation. Even though kinetics changes that focus a bit, you will not have to design experiments that relate to intermediates formed in the chemical reaction.
Unit 6 is all about Thermodynamics. As we have discussed in a prior episode, energy is neither created nor destroyed. Based on this first law of thermodynamics, Unit 6 looks at the role energy plays when chemical bonds are being broken and formed, discusses how the amount of energy can be determined experimentally and introduces the concept of enthalpy. Since most reactions in AP Chemistry are under constant pressure, you will not have to distinguish between enthalpy and internal energy.
Unit 7 adds another layer to our understanding of the transformation of matter. It focuses on chemical equilibrium, which is a dynamic state in which chemical bonds are broken at the same rate as they are formed. Understanding chemical equilibrium will enable us to predict how a system reacts if we are changing the conditions: for example by decreasing or increasing the temperature, pressure, or concentration of reactants and products. This has very practical applications in industry, when setting reaction conditions that favor the formation of products we want to produce. In this unit we will also circle back to solubility and look at solubility equilibria.
Unit 7 lays the foundation for Unit 8: Acids and Bases which we have already encountered in Unit 4 with chemical reactions. It all connects! Now we are taking a closer look and are applying our equilibrium knowledge. The unit starts with an introduction then explores into the calculations of pH for strong and weak acids and bases as well as acid-base titrations. The unit concludes in a student all-time favorite (cough, cough): buffers. The good news is that you will not have to do calculations involving concentrations during the titration of polyprotic acids nor changes in pH resulting from the addition of an acid or base to a buffer.
Unit 9, last but not least! Unit 9 is Applications of Thermodynamics! As the title already indicates, this is an extension to unit 6, but it also connects concepts from Units 5, 7 and 8. The first focus revolves around the question: Is a chemical reaction favorable and occur without intervention? This involved energy and entropy. The second focus is the “electrochemistry” chapter in your textbook. In this part you will be learning about electrical energy, which can be generated by chemical reactions. You will need your knowledge about redox reaction from Unit 4, Energy from Unit 6, Equilibrium from Unit 7 as well as the first part of Unit 9. See? It's on purpose that this is the final section of the AP Chemistry curriculum. While it might sound intimidating, it is actually fun to see how these chapters all connect in one topic and a real chance for you to have that light bulb moment!
To recap….
The AP Chemistry curriculum has nine units. The earlier units have strong connections with first year chemistry course content while the later units introduce new materials. All units are connected to one another through the big ideas and science practices.
Coming up next on the APsolute RecAP Chemistry Edition:
Moles, Molar Mass and Mass Spectroscopy
Today’s question of the day is about Exam structure
Question of the day: Which unit is most heavily weighted on the exam?