Best Sarah Rayder Podcasts (2025)

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The APsolute RecAP: Chemistry Edition - Episode 62: Molecular Structure and Acid Strength 10:50

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4y ago10:50

10:50

All hydrohalic acids, but hydrofluoric acid, are strong acids. Why is that (0:31)? Strong acids fully dissociate and have a large Ka, weak acids only dissociate to a small percentage (1:20). When looking at strength, we are comparing the stability of the conjugate acid/base pair partners (2:00). For binary acids across a period (2:37) as well as do…

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The APsolute RecAP: Chemistry Edition - Episode 61: Unit 7 Selected FRQs 12:04

4y ago12:04

12:04

The FRQ questions on the AP exam often combine content from two or three different units. In today’s episode, we are emphasizing questions that require knowledge and skills from Unit 7: Equilibrium. You will rarely find an FRQ that solely focuses on Unit 7, since it lays the foundation for Unit 8, acids and bases as well as parts of Unit 9, Applica…

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The APsolute RecAP: Chemistry Edition - Episode 60: Factors Affecting the Dissolution of a Salt 9:40

4y ago9:40

9:40

This episode is an application of earlier discussed concepts. In episode 33 we talked about disruptions affecting equilibrium: concentration, temperature and pressure. In episode 34, solubility equilibria, we talked about the dissolution of a salt. In this episode we set our focus a bit differently: We look at environmental factors, like pH or othe…

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The APsolute RecAP: Chemistry Edition - Episode 59: Unit 6 selected FRQs 13:45

4y ago13:45

13:45

Unit 6 is all about the big idea Energy (0:46). Episode 59 discusses the questions 2021 - Question 4, 2017 - Question 5 and 2013 - Question 3. These are released FRQs from previous exams and copyright of the College Board. Question 4 of the 2021 exam starts with our favorite equation: mcAT (1:34). In part b) you calculate the mass of iron and in pa…

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The APsolute RecAP: Chemistry Edition - Episode 58: Energy of Phase Changes 10:01

4y ago10:01

10:01

We are taking a closer look at what happens when hot water is cooled down or ice is heating up (0:30). After a brief review of the terminology of phase changes (1:11) we are taking a closer look at the particles in solid, liquids and gases (1:29). Focusing on the energy component of phase changes, we are describing the five segments of a heating cu…

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The APsolute RecAP: Chemistry Edition - Episode 57: Unit 5 selected FRQs 12:13

4y ago12:13

12:13

Unit 5 is often a stand alone unit and offers a unique perspective on reactions. Episode 57 discusses the questions 2010B - Question 6 and 2019 - Question 6. These are released FRQs from previous exams and copyright of the College Board (0:44). Question 6 of the 2010B exam focuses on the synthesis of hydrogen chloride from its elements (1:33). We a…

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The APsolute RecAP: Chemistry Edition - Episode 56: Concentration Changes Over Time 9:25

4y ago9:25

9:25

An AP Chemistry classic experiment for concentration changes over time is determining the rate law of fading Crystal Violet. (1:07) If the reaction is zero order, the plot of our concentration of our reactant vs time is linear. (2:51) If the reaction is first order with respect to our crystal violet, a plot of the natural log of the concentration o…

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The APsolute RecAP: Chemistry Edition - Episode 55: Unit 4 Selected FRQs 11:33

4y ago11:33

11:33

Unit for is a mix of foundational skills, like stoichiometry, and an introduction to later topics (0:32). The questions in this episode are: 2018 - Question 3 d) through i) and 2014 - Question 1 a) - f). These are released FRQs from previous exams and copyright of the College Board (1:32). 2018 starts with three questions from a different unit. Par…

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The APsolute RecAP: Chemistry Edition - Episode 54: Unit 3 Selected FRQs 12:02

4y ago12:02

12:02

The FRQs discussed in this episode are the question 4s from the 2019, 2018 and 2017 AP Exam. These are released FRQs from previous exams and copyright of the College Board (0:23). Question 4 of the 2018 exam focuses on comparing the IMFs of CS2 and COS, asking you to explain why CS2 has a higher boiling point (1:48). The second part has you calcula…

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The APsolute RecAP: Chemistry Edition - Episode 53: Beer-Lambert Law 8:43

4y ago8:43

8:43

Coffee needs to be “just right” and we can tell how strong it is by the color (0:30). We can use the color to determine concentration also in Chemistry (1:09). The color we see is determined by the wavelength an object reflects, while absorbing all other colors (1:23). The Beer-Lambert Law absorbance to molar absorptivity, path length and concentra…

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The APsolute RecAP: Chemistry Edition - Episode 52: Deviation From Ideal Gas Law 7:42

4y ago7:42

7:42

Teachers wish students would always behave ideal, but in reality life happens and it gets messy (0:32). The same is true for gases: There is a difference between real and ideal gases (1:12). The Ideal Gas Law assumes that particles don’t experience intermolecular forces nor that they take up volume (1:34). But real gases do and this leads to deviat…

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The APsolute RecAP: Chemistry Edition - Episode 51: Types of Solids and Their Properties 10:01

4y ago10:01

10:01

Sitting in your room, you might have salted peanuts as a snack, a pencil, tea with sugar and you listen to this episode with earphones in (0:31). Sodium chloride, sugar, graphite and copper represent four types of solids. Sodium chloride is an ionic solid with low vapor pressure, high melting points and high boiling points, because of the strong at…

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The APsolute RecAP: Chemistry Edition - Selected Unit 1 and 2 Free-Response Questions 12:56

4y ago12:56

12:56

The FRQs discussed in this episode are 2008 - Question 2 and 5 as well as 2019 question 5. These are released FRQs from previous exams and copyright of the College Board (0:22). Question 2 of the 2008 focuses on the experimental approaches, first the determination of the formula of a hydrate (2:06) and then gravimetric analysis (3:33). Question 5 o…

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The APsolute RecAP: Chemistry Edition - Lewis Diagrams and Formal Charges 9:34

4+ y ago9:34

9:34

Lewis Diagrams give us information about the arrangement and bond order of compounds (0:23). There are four steps to write Lewis Structure: 1) Sum up available valence electrons (1:16), 2) write symbols and connect them with a single bond (1:57), 3) complete the octet for surrounding atoms (2:27), and 4) add remaining electrons as lone pairs on cen…

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The APsolute RecAP: Chemistry Edition - Gravimetric Analysis 8:52

4+ y ago8:52

8:52

Do you have your own bathroom? Then you might be familiar with soap scum, which is the result of a combination of having hard water and soap (0:44). To determine how hard water is, we can use gravimetric analysis, which is an experimental procedure used to determine the amount of a substance, for example an ion, by precipitating it from an aqueous …

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The APsolute RecAP: Chemistry Edition - Empirical and Molecular Formulas 9:24

4+ y ago9:24

9:24

Switching glucose and formaldehyde would be really bad (0:42)! So let’s make sure we know the difference between empirical and molecular formulas! Our episode starts with a definition of empirical formulas (1:20) and the comparison of ionic and molecular compounds (1:49). It briefly recaps the significance of a chemical formula (2:16) and then reca…

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The APsolute RecAP: Chemistry Edition - Test Taking Tips 2021 8:05

4+ y ago8:05

8:05

The episode discusses and compares the structure of the two exam formats: the paper exams in May and the digital exam in June (0:50). Differences between the administration of the digital exam and paper exam are described (1:11), especially the calculator policies (2:16). We are taking a quick look at timing, which is the same for the paper exam an…

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The APsolute RecAP: Chemistry Edition - FRQ Annotations 9:42

4+ y ago9:42

9:42

The FRQ section has 3 long and 4 short question sets which you will have 105 minutes to complete (0:52). Past free response questions are available on the College Board website. (1:32) Make sure you carefully read the question and answer directly with precise language. (2:59) For calculations, make sure you show all your work, use units throughout …

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The APsolute RecAP: Chemistry Edition - Multiple Choice Strategies 7:22

4+ y ago7:22

7:22

You’ve made it through the year! Let’s hone our Multiple Choice skills to make sure we can show off our knowledge and skills! Our episode starts by discussing pacing: The multiple choice section consists of 60 questions within 90 minutes (0:54). Then we are taking a closer look at strategies: using the process of elimination (2:09), carefully readi…

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The APsolute RecAP: Chemistry Edition - Listener’s Choice III 13:09

4+ y ago13:09

13:09

Our listener’s choice recaps three topics: (R)ICE tables, titrations and buffers. We start with the RICE table - what does it actually stand for? (0:49). RICE tables are best explained with an example. In our case: The reaction of gaseous hydrogen with gaseous chlorine to form gaseous hydrogen chloride - a reaction that has a K = 49. And we are cal…

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The APsolute RecAP: Chemistry Edition - Electrolysis 8:35

4+ y ago8:35

8:35

Electroplating is an important industrial process to prevent corrosion and upvalue jewelry and cutlery (0:30). Electroplating takes place in electrolytic cells, which need an external power source (1:25). Our episode qualitatively describes electroplating using the example of a zinc spoon and silver (1:52). Quantitatively, we discuss Faraday’s law …

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The APsolute RecAP: Chemistry Edition - Galvanic and Electrolytic Cells 7:52

4+ y ago7:52

7:52

Have you ever built a lemon battery? How do they work? (0:32). We are distinguishing between two types of electrochemical cells: galvanic, also called voltaic cells, and electrolytic cells (1:05). Both cells have an anode, where the oxidation takes place, and a cathode, where the reduction occurs. (2:01). But where are the differences? Our episode …

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The APsolute RecAP: Chemistry Edition - Gibbs Free Energy 9:54

5y ago9:54

9:54

Our episode starts with a clarification of using the terms thermodynamically favored vs spontaneous (1:19). To determine if a reaction is thermodynamically favored, we calculate Gibbs Free Energy using the Gibbs Free Energy of formation (2:45). Taking a closer look at Gibbs Free Energy we relate it to enthalpy and entropy and look at four different…

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The APsolute RecAP: Chemistry Edition - Entropy 7:06

5y ago7:06

7:06

Click, click, click - you picture has been taken! Our episode starts with describing entropy with respect to the dispersal of matter and compares it to the snapshots or microstates (0:30). The phase changes are examples of increases of dispersal of matter (1:06). Entropy can also be defined as an increase of the dispersal of energy and therefore we…

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The APsolute RecAP: Chemistry Edition - Buffers 9:07

5y ago9:07

9:07

Buffers are a common term in the english language, but what do they mean in Chemistry (0:39)? Episode 38 describes the chemical set up of buffers (1:31) and takes a closer look at how the buffer works on a particle level (2:03). To calculate the pH of a buffer the episode describes the Henderson-Hasselbalch equation (3:04). Using the theme of equal…

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The APsolute RecAP: Chemistry Edition - Acid-Base Titrations 8:34

5y ago8:34

8:34

Acid-base titrations are an experimental approach to determine the concentration of an unknown acid or base (0:56). Your episode starts by introducing the terms analyte and titrant (1:49) and looks at two examples: In the first example, we are titrating a strong acid with a strong base (2:03). We describe the shape of the titration curve (2:14) and…

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The APsolute RecAP: Chemistry Edition - pH and pOH 10:12

5y ago10:12

10:12

We are starting with a recap of episode 35 and are defining acids and bases and their connection to pH and pOH (1:02). Taking a closer look at the pH scale, our episode discusses the use of logarithm for pH and pOH (1:53). This lays the foundation for the calculation of pH and pOH for strong acids and bases. For weak acids and bases the episode dra…

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The APsolute RecAP: Chemistry Edition - Acids and Bases - The Basics 10:17

5y ago10:17

10:17

We start our recap with a recap: What are acids and bases and acid-base reactions (1:03)? Diving a bit deeper, we take a closer look at the dissociation of acids (2:20), which releases H+ ions and therefore lowers the pH. Vice-versa we look at the dissociation of bases in water (3:34 ) and it’s connection to pOH and pH (3:34). Taking a closer look …

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The APsolute RecAP: Chemistry Edition - Solubility Equilibria 8:30

5y ago8:30

8:30

Our episode starts with addressing the question: What IS solubility? (1:19). The episode introduces solubility equilibria with respect to the Solubility-Product Constant, K, expression (1:57) and discussion how its magnitude relates to solubility (3:05). If you have the Ksp you can calculate the molar solubility - in mol/L - as well as the mass sol…

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The APsolute RecAP: Chemistry Edition - Le Chatelier’s Principle 8:44

5y ago8:44

8:44

Let’s be disruptive: What happens when you disturb the equilibrium of a chemical reaction? Our episode talks you through several different scenarios and their effect on the reaction as well as K and Q: We can add reactant and product (2:01) or remove reactant and products (2:58). We can also change the temperature of our reaction and either add hea…

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The APsolute RecAP: Chemistry Edition - Equilibrium Constant 9:10

5y ago9:10

9:10

Try to keep your balance! The episode starts with an analogy of villagers commuting from Moleville to Chemtown (0:59). Tying it to a chemical reaction, we define equilibrium as the point where the rate of the forward and the rate of the reverse reaction are the same (1:43). To determine if, at equilibrium, a reaction has more reactants or products,…

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The APsolute RecAP: Chemistry Edition - Enthalpy 10:12

5y ago10:12

10:12

Heat, Energy and now Enthalpy? What is going on? Our episode starts by defining and distinguishing between these concepts (0:54) before taking a closer look at enthalpy itself. The episode connects the mathematical sign of enthalpy to the heat being absorbed / released (1:39) and discusses the extensive character of enthalpy (2:06) as well the valu…

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The APsolute RecAP: Chemistry Edition - Heat Capacity and Calorimetry 8:51

5y ago8:51

8:51

Heat transfer is all around! The episode starts by describing the heat transfer on a particle level (0:58). Heat transferred can be quantified using the heat transfer equation (1:42). The heat transfer equation takes into account the mass of the substance (2:32), the specific heat capacity (4:12) as well as the change in temperature (6:05). It can …

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The APsolute RecAP: Chemistry Edition - Energy of Chemical Reactions 7:17

5y ago7:17

7:17

We are surrounded by exothermic and endothermic reactions. Episode 29 starts by describing the first law of Thermodynamics (1:39) as well as the terms system and surroundings (1:53) using the combustion of hydrogen as an example. We take a closer look at the bond breaking and bond formation of the combustion (2:20) and describe the energy diagrams …

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The APsolute RecAP: Chemistry Edition - Listener’s Choice II 7:39

5y ago7:39

7:39

Our episode recaps two connected concepts: Boiling points and the strength of intermolecular forces. We start with the chemistry definition of boiling points (0:53) and take a closer look at what happens at the start of heating (1:13), while heating (1:30) and at the boiling point of a pot of water (1:41). The episode then takes a closer look at th…

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The APsolute RecAP: Chemistry Edition - Midterm Review 11:01

5y ago11:01

11:01

Episode 27 reviews Units 1-4 of the AP Chemistry curriculum. Starting off with Unit 1 it gives an overview over counting atoms and isotopes (1:28). Diving deeper, we review atomic structure and electron configurations (2:17) as well as Coulomb’s Law (3:04). In Unit 2 the episode focuses on the types of bonds (3:33) and how they are determined. The …

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The APsolute RecAP: Chemistry Edition - Listener’s Choice 1 9:28

5y ago9:28

9:28

Our listener’s choice recaps three topics: Ideal Gas Laws, Solubility and Internal Energy. We start by recapping what an ideal gas is compared to a real gas (1:28) and review the equation PV=nRT by describing the relationship between selected variables (2:11). We take a closer look at the relationship between particle number and pressure and review…

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The APsolute RecAP: Chemistry Edition - Catalysis 6:47

5y ago6:47

6:47

Episode 25 starts with the definition of a catalyst and describes how we can identify the catalyst in a set of elementary steps (1:22). Catalysts work by increasing the number of successful collisions, by providing a pathway with a lower activation energy (2:18) or by providing an intermediate with more favorable orientation (2:50). Catalysts can b…

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The APsolute RecAP: Chemistry Edition - Reaction Mechanism and Rate Law 7:23

5y ago7:23

7:23

Did you know that you can compare a chemical reaction with your daily experience in the lunch line? Episode 24 recaps the reaction mechanism and how it relates to the rate law. It starts with a brief recap of factors affecting the rate of a reaction (1:28). A reaction itself can have several elementary steps that make up the overall reaction (2:00)…

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The APsolute RecAP: Chemistry Edition - Reaction Rate and Rate Law 9:13

5y ago9:13

9:13

Diamonds are forever, aren’t they? Episode 23 recaps reaction rates and rate laws. We start with the definition of a reaction rate using our stoichiometry sandwiches as an analogy (1:30). Focusing on reactants or products, we can measure the rate of appearance or disappearance (2:20). Using collisions, we discuss the factors that influence the rate…

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The APsolute RecAP: Chemistry Edition - Types of Chemical Reactions 12:30

5y ago12:30

12:30

Episode 22 starts with a recap of the five types of chemical reactions described in episode 6. But then we are getting in deep! The episode introduces acid-base reactions and defines them as reactions in which protons are being transferred (1:53). Not protons, but electrons are being transferred in redox reactions (3:15). To identify which atom has…

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The APsolute RecAP: Chemistry Edition - Dive Deeper: Stoichiometry 9:13

5y ago9:13

9:13

Stoichiometry, every chemistry student’s nightmare! But we’ve got you! The episode reviews the mole concept and describes the meaning of coefficients in a balanced chemical equation (1:03). Using sandwiches as an analogy, it shows how to relate the amount of reactants to products (2:42) and uses the same concept for the synthesis of ammonia (5:08).…

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The APsolute RecAP: Chemistry Edition - Types of Chemical Equations 9:08

5y ago9:08

9:08

What IS a chemical reaction? Our episode starts with differentiating between physical (1:08) and chemical changes (1:47). To represent chemical reactions, chemists use three different types of chemical equations: Molecular equations that show neutral compounds (4:50), complete ionic equations that show soluble ionic compounds as free floating ions …

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The APsolute RecAP: Chemistry Edition - Aqueous Solutions 8:53

5y ago8:53

8:53

Water is oh so special, being the star of this episode! Episode 19 starts with a recap of Episode 8 definition of solution components, electrolytes and concentration (1:27). Concentration can also be determined relatively by using particle diagrams (2:35). Another application of particle diagrams is to visualize the interaction between solvent part…

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The APsolute RecAP: Chemistry Edition - Kinetic Molecular Theory 7:22

5y ago7:22

7:22

Episode 18 starts with a recap of a recap: Reviewing Episode 7 Kinetic Molecular Theory (1:06) and the relationship between pressure, temperature and volume. Taking a closer look at temperature, it connects it to average kinetic energy (2:15), which can be calculated using mass and particle speed. The episode then describes graphs showing Maxwell-B…

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The APsolute RecAP: Chemistry Edition - Intermolecular Forces 10:22

5y ago10:22

10:22

This episode recaps the five types of intermolecular forces, discusses factors influencing the strength of force and provides examples. It starts with the weakest IMF, London Dispersion Forces (2:05) and introduces polarizability (2:31). In order of increasing strength we recap dipole-induced dipole interaction (5:00), dipole-dipole interaction (6:…

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The APsolute RecAP: Chemistry Edition - VSEPR Theory 8:56

5y ago8:56

8:56

In this episode we define the acronym V-S-E-P-R and take a closer look at bonding and non-bonding electron pairs around a central atom (1:10). We distinguish between electron-domain geometry and molecular geometry (1:50). The episode describes the six electron-domain geometries (2:40) as well as the molecular geometries and bonding angles that aris…

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The APsolute RecAP: Chemistry Edition - Chemical Bonds 10:07

5+ y ago10:07

10:07

Episode 15 starts with a quick recap of electronegativity and how it determines the type of bond formed (1:10). Then it takes a closer look at covalent bonds and electronegativity, introducing polar and nonpolar bonds (2:20). Diving even deeper into covalent bonds, we focus on the relationship between distance between nuclei and potential energy an…

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The APsolute RecAP: Chemistry Edition - Coulomb’s Law and Periodic Trends 9:25

5+ y ago9:25

9:25

The Periodic Table is trendy! Episode 14 recaps Coulomb’s Law (1:10) and describes how it applies to atomic structure (2:00). We can use Coulomb’s Law to predict atomic radii (3:30) ionic radii (4:00). The episode also defines ionization energy, electronegativity and electron affinity (4:45), describes their periodic trends and ties them to Coulomb…

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The APsolute RecAP: Chemistry Edition - Atomic Structure, Electron Configuration and PES 10:14

5+ y ago10:14

10:14

The episode starts with a recap of atomic structure (1:13) before it focuses on electrons. Using Heisenberg’s Uncertainty Principle as a background (2:10) it recaps electron configurations by comparing it to a small town set-up (3:05). We also discuss the Aufbau Principle (5:30) and connect the electron configurations to the periodic table (5:45). …