To connect the different concepts throughout the year, we are looking first at the big ideas
To connect the different concepts throughout the year, we are looking first at the big ideas (0:30): Big idea 1: scale, proportion, and quantity which focuses on the macroscopic as well as atomic scale (1:00). Big idea 2 - structure and properties - connects the atomic makeup of substances with observable properties (1:30). Big idea 3 is all about transformations, die rearrangement of matter (2:14) and big idea 4 connect content related to energy (2:55). In the second part, we are reviewing the six scientific practices that students will have to develop: describing models and representation (4:00), determining scientific questions and methods (4:43), representing data and phenomena (5:34), analyzing and interpreting models and representations (6:00), mathematical routines (6:32) as well as developing explanations or scientific arguments (7:44).
Question: What big idea/science practice is the following learning objective? “Calculate the number of solute particles, volume or molarity of solutions.” (9:02)
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Hi and welcome to the APsolute Recap: Chemistry Edition. Today’s episode will recap the four big ideas and six science practices that the AP exam covers.
Lets zoom out
Do you love a “light bulb moment” as much as I do? That feeling when all of a sudden something clicks into place and starts to make sense? We want to help you have those light bulb moments by outlining and describing the Big ideas of the AP Chemistry curriculum. These big ideas are overarching concepts that run across different units and connect them. They will help you to deepen your understanding and look at it from different perspectives.
Lets zoom in
Big Idea 1 is called scale, proportion, and quantity - or SPQ. Quantity matters on two levels - the macroscopic level and the atomic scale. A chemical reaction, for example, can be limited by the amount of reactant present. Or you want to calculate how much product you’ll get! This part of chemistry, called Stoichiometry, usually takes some practice, but it will be returning in several units so you’ll have a lot of chances. Quantity matters on an atomic scale, for example, when it comes to solubility.
Big idea 2 focuses on structure and properties, abbreviated as SAP. Under big idea 2 we summarize the notion that our macroscopic observations can be explained by the structure of atoms and molecules and their interactions. We can, for example, predict how vigorous a reaction is using periodic trends, what properties a substance has when knowing about the type of chemical bonding or how strong an acid is when knowing its structure. This relationship goes both ways: we can make inferences about atomic structure and interactions when observing macroscopic properties, but we can also use what we know about atomic structure to form a hypothesis about what we will observe.
Big idea 3 is, so to speak, the core of chemistry. It focuses on transformations - TRA. This is what distinguishes chemistry from other sciences: it is about rearranging matter, resulting in a new substance with different chemical and physical properties. So, as you can imagine, this has to be one of the connecting concepts! Chemical reactions are transformations - no matter if it is a combustion, redox reaction, acid-base reaction or any other type. But transformations go deeper - we are also looking at the rate of a reaction, discussing what makes a successful transformation and when a reaction has reached equilibrium.
The last big idea, big idea 4, is energy - ENE. The first law of thermodynamics states that energy can neither be created nor destroyed. It is conserved. In AP Chemistry we are going to look at the distribution and redistribution of energy like when measuring the change in temperature of a system. We can also use energy with the closely related concept of enthalpy to determine if chemical reactions are favorable.
Big ideas are overarching concepts, but there are also foundational skills that the students need to have to be successful on the AP exam. These skills are known on the CED as science practices. They include models and representations, question and method, representing data and phenomena, model analysis, mathematical routines and argumentation. In the MC and FRQ section the science practice mathematical routines are weighted the heaviest. Multiple Choice also often asks for model analysis, whereas the FRQs second focus is on argumentation. You will be practicing these skills across all big ideas throughout the entire year.
In science practice 1 you will have to describe models and representations, within and across different scales. What does that mean? Chemistry can be somewhat abstract. Models, like particulate diagrams, electron configurations or Lewis Dot structures can help us visualize chemical reactions. We can also use them to make predictions about observable properties on the macroscopic level. For example, if we can determine the number of valence electrons using the electron configuration, we can make predictions about reactivity and type of chemical bond. To practice this skill, I recommend using the diagrams in your textbook. Try to write your own description to go along with the graph or describe them to a friend, maybe even someone who is not in AP Chemistry.
Science practice 2 focuses on determining scientific questions and methods. This might happen during lab activities - but it doesn’t have to. You are asked to generate a scientific question, plan an investigation, make an observation, construct an explanation, identify potential sources of error and much more! Experiments are at the heart of chemistry - and, let’s be honest, the fun part of this course! Practice this as much as possible, both during and after labs: What is the question you are answering? Or what could be a question extending the lab? Reflect on your data: Is there an outlier? What could be the reason for it? Compare your data to others: Why are your measured values higher or lower? And it doesn’t always have to be directly related to chemistry. If you like baking cupcakes, why not make a small experiment by adding various amounts of vanilla extract and see which one tastes best?
Science practice 3 - representing data and phenomena - is closely related to science practice 1, but focuses more on the representation and widens the scope a bit. You shouldn’t be able to just describe representations, models and graphs, but to create them yourself! This can be drawing graphs, like a titration curve, drawing particle diagrams of reactions, or writing the electron configuration for a given element. Given the nature of this science practice, it can only be tested in the FRQ section of the exam.
Science Practice 4 asks you to analyze and interpret models and representations. So we go from describing, to creating, to analyzing and interpreting a model and using it for explanations. Explaining is really the emphasis here - like when explaining an observation made in the lab by drawing a matching particle diagram or explaining a periodic trend. Make yourself aware of the difference between describing and explaining! We will help.
As mentioned before, science practice 5 is heavily focused throughout the exam. It is mathematical routines, where you are asked to solve problems using mathematical relationships. This is not only being able to solve an equation. You should also be able to use mathematical reasoning: why are you using this equation at this point? What is the relationship between the variables? What happens if one of the variable’s values increases or decreases? In chemistry, this science practice also includes being able to write a balanced chemical equation. How do you prepare for this skill: practice, practice, practice. But it's important to go beyond that: explain why you are using this equation and do not just plug in numbers. Really think about your calculated value: what does that mean? Does it make sense? Two things to keep in mind: First, there is no need to memorize equations - you will have an equation sheet on exam day. Second, you will not be allowed to use a calculator in the MC section. On the one hand you will see this reduces the number of questions that can actually be asked - some calculations you definitely cannot do in your head. On the other hand, that also means you will have to practice mental math throughout the year!
The final science practice is developing an explanation or scientific argument. Here you are asked to make a scientific claim, support your claim with evidence and provide a reasoning to justify the claim. This skill ties into all of the other science practices. You can use models and representations as a source of evidence, you provide reasoning by showing the connection between macroscopic and particle level and you connect your experimental results, which may involve calculations, to content and concepts. This is a skill that is especially valuable outside of chemistry and which you can practice every day. If you can construct a solid argument, maybe you can convince your teacher to get out of homework, get extra credit or get your parents to increase your allowance.
To recap.
There are four big ideas on the AP Exam: scale, proportion and quantity, structure and properties, transformations, and energy. All four of these big ideas are recurring throughout the school year and help you to make connections and deepen your understanding. There are also six science skills on the AP exam. These skills will be found in both the multiple choice and free response section. It is your responsibility as a student to shape your studying in a way that will allow you to practice these skills during the learning process.
Coming up next on the APsolute RecAP Chemistry Edition: Units and Exclusions
Today’s question of the day is about big ideas and science practices.
Question: What big idea/science practice is the following learning objective? “Calculate the number of solute particles, volume or molarity of solutions.”