In addition to making up the majority of the MCAT Chemistry and Physics section, chemistry also makes up 35% of the MCAT biology section, making it the second-most tested subject on the MCAT after biology. As such, you need a sturdy grasp on the concepts and categories of chemistry knowledge tested throughout the MCAT in order to score well. In our guide, we’ll cover the full range of chemistry concepts tested on the MCAT, as well as strategies and study tips to ensure you crush all the chemistry that the AAMC can throw at you.
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How Much Chemistry is on the MCAT?
Chemistry is of course the central component of the Chemical and Physical Foundations of Biological Systems (CPBS) section, often simply referred to as the Chemistry and Physics section. In fact, chemistry comprises well over 70% of this section:
This section of the MCAT assesses your ability to solve problems using both knowledge of foundational concepts, scientific inquiry, and reasoning skills. The CPBS section is the first you’ll tackle when taking the MCAT, so it’s vital to make this section go as smoothly as possible. Like each other science-based section of the MCAT —i.e., all except CARS—CPBS is comprised of 59 questions which will vary between discrete or 1-off questions and passage-based questions. Like the other science portions of the MCAT, you will have 95 minutes to complete this section.
Chemistry also factors heavily into the Biological and Biochemical Foundations of Living Systems (BBLS) section:
So, with nearly ¾ of the CPBS section and 1/3 of the BBLS section covering chemistry, it’s hard to underestimate the importance of these various modalities of chemistry when it comes to studying. Our primary focus in this guide is the CPBS section, and so biochemistry will only be addressed occasionally. Regardless, with 10% of BBLS questions being rooted in general and organic chemistry, much of what we discuss here will apply to the MCAT chemistry questions in both sections.
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A Step-by-Step Guide to Determine Which Chemistry Concepts You Need to Review
The array of chemistry knowledge on the MCAT can make designing a study program feel overwhelmingly complicated. Fortunately, there are some basic best practices that will allow you to organize your energy and time effectively.
The first step is always to take a full-length MCAT diagnostic test. There’s simply no way to have a concrete sense of your baseline knowledge until you’ve simulated the testing experience and actually forced yourself to think under pressure. This means taking your diagnostic with a strict time limit, and in conditions that mimic the actual testing environment—a quiet room, with only a copy of the periodic table and some blank paper to accompany you. The AAMC’s practice exams are best for this—while other prep companies and question banks offer an array of tests, the best option for your initial diagnostic is one that comes straight from the horse’s mouth, so to speak.
As you review your results, go very slowly through each incorrect answer and note which of the above categories it relates to. Patterns should emerge as you do this, as incorrect answers often rest within a topic such as:
From there you can begin outlining when to start studying for the MCAT in earnest. We recommend no more than 6 months ahead of your ideal testing date, as spreading things out beyond this window usually results in losing material you studied at the start before the big day.
Once you’ve committed to an MCAT study schedule, you can begin fine-tuning your study sessions to include MCAT chemistry questions, MCAT physics equations, and MCAT biology questions in varying amounts depending on your needs. Question banks like UWorld can be very helpful for this as well, allowing you to focus on specific subtopics and examine explanations and rationales following incorrect responses. And although we recommend against using them for an initial diagnostic test, the practice exams offered by companies like UWorld can indeed be helpful if you need to build or rebuild subject-specific muscles in biochemistry, organic chemistry, and so on. Nevertheless, we recommend using another of the AAMC’s practice MCAT exams at the midway point in your preparation period in order to provide an updated diagnostic baseline. As always, the more feedback you have the better, so consider a consultation with an MCAT prep service to see if you might benefit from having additional expert feedback and guidance. It’s best to seek this help out before the midway point in your schedule, but if things seem especially difficult at the midway point, you’ll still have enough time to benefit from employing such additional help before your big day.
As your study schedule approaches final months of preparation, you’ll want to wind down lengthy review periods and work on more practice questions, elongating your sessions to begin approximating the grueling duration of how long the MCAT is. This can be difficult with regard to the other responsibilities you’ll have in relation to your undergraduate coursework, so try to minimize additional stress and schedule complexity as best you can during the final month or so of your plan. You don’t need to live like a monk to get a good MCAT score, but you will need to temporarily forego or at least restrict your social engagements to maximize your studying.
How to Prepare for MCAT Chemistry Questions
The more anxious part of your mind will giddily inform you throughout your test that no question is simple, and that if an answer seems simple or obvious then you’re either thinking about it incorrectly or don’t understand it. In the event this little goblin pops up during your studying or test-taking, slow down! Rushing is the most common reason for getting questions wrong, especially if you’re a seasoned science student who has diligently studied for months prior to exam day. Most questions that seem really complicated—even unsolvable—are in fact extremely simple. There are tricky questions on the MCAT, but the test writers don’t set out to trick you with wording. Stay calm, reread a question if your first instinct is to see it as a 400-level midterm brain-melter, and trust that the test is not trying to confuse you into answering incorrectly.
Part of that confidence boost will come from having your hypotheses confirmed at least most of the time—that is, when you approach a discrete question, always take a moment to come up with a general hypothesis about the correct answer after carefully reading the question. This will help you excise answers that are absolutely incorrect faster, and give you more time to decide between the likely correct ones.
![MCAT chemistry infographic](data:image/svg+xml,%3Csvg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 500 398"%3E%3C/svg%3E)
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Appendix: A Complete List of Chemistry Concepts on the MCAT
The AAMC structures the MCAT around 10 Foundational Concepts which are distributed among the 4 sections of the exam. The Chemical and Physical Foundations of Biological Systems section is designed around two of these foundational concepts. It’s important to note at the outset that these foundational concepts are defined in somewhat lengthy terms, so it’s crucial to both understand them as presented by the AAMC, and be able to paraphrase them in your own words. The MCAT is often referred to as being “a mile wide and an inch deep,” meaning that the breadth of topics and concepts is vast, but the depth into which any question will go is consistently limited. As indicated in the charts above, the vast majority of chemistry knowledge tested on the MCAT will come from introductory and general chemistry, as well as first-year organic and biochemistry. You don’t have to worry about advanced molecular spectroscopy, but you will need to know the basics of mass spectroscopy very well. For a full outline of the MCAT chemistry topics you’ll need to know, let’s dive—well, more like wade—into the shallow but wide pool of Foundational Concepts 4 and 5.
Foundational Concept 4
Physical principles govern the processes used by complex organisms—like the human body—to transport materials, sense and process environmental data and internal signals, and respond to changes. Because these intra-organism processes operate according to the laws of physics, they can be represented and quantified using equations and behavioral models. The AAMC definition gives the example that “the principles of electromagnetic radiation, and its interactions with matter, can be exploited to generate structural information about molecules or to generate images of the human body.” Therefore, atomic structures can similarly be used to predict or model the physical and chemical properties of atoms, which for this example would extend to calculating processes like ionization based on electromagnetic energy.
This may all feel like a real mouthful, but this kind of foundational connectivity between physics and chemistry is a key part of understanding the nature of the CPBS section. You will have a handful of discrete questions that demand simply calculating things like molar mass etc., but for passage-based problems you will need to understand the synergistic nature of physical and chemical laws in order to determine your approach to answering.
Medicine relies on this fundamental knowledge to shape diagnosis and treatment of often complex/systemic disease pathologies. Therefore, questions in this section will regularly utilize problems referring to the physiological functions of the neurological, cardiovascular, and respiratory systems in human health.
Foundational Concept 4 is further subdivided into 5 Content Categories:
Focuses entirely on Physics domains like translational motion, force, equilibrium, work, energy of point object systems, and periodic motion. Our Physics prep guide discusses this category and other physics-dominated categories of the CPBS section in greater depth. Focuses on the behavior of fluids and gasses in relation to pulmonary and circulatory function. Topics within this category include: Fluids Gas Phase The Gas Phase section of Category 4B will be heaviest on chemistry knowledge, specifically general chemistry information likely covered in a two-semester fundamentals course taken early in your undergraduate education. These courses vary somewhat from school to school, but in most cases it will be the 102-level course focusing on reactivity that will be of interest for this category. Focuses on the fundamentals of electrical currents, voltages, energy conversions relating to chemical transformations, and how the nervous system utilizes long-distance transmission of electrical impulses. Topics within this category include Electrostatics, Circuit Elements, and Magnetism, all of which are physics topics. However, 4C also includes one very crucial chemistry-based section: Electrochemistry Focuses on the interactions of sound and light with matter. While most of this category focuses on physics, it includes a topic focusing heavily on organic chemistry. For chemistry-specific review and studying, then, you’ll want to refresh your understanding of the way spectroscopic changes—that is, changes in matter based on interactions with light—can be used in identification at the atomic and molecular levels. The AAMC breaks down the chemistry material in this category as follows: Molecular Structure and Absorption Spectra Category 4E is the heaviest on chemistry knowledge in Fundamental Concept 4’s categories. It includes special focus on atoms generally, atomic and chemical behavior, and electronic structure. Following the basic schema of atomic nuclei and the role of protons and neutrons in categorizing atoms, 4E begins to delve into reactivity on a number of levels. Electrostatic forces involving electrons and nuclei are responsible for chemical interactions between atoms, and since neutrons are uncharged, they have no effect on the composition of the atom, but they do have an effect on the stability of the nucleus. This category will also demand knowledge of unstable nuclei and nuclear decay, including the ways in which various byproducts of decay—like alpha, beta, and gamma rays—interact with living tissue and affect chemical bonding and ionization. Accordingly, mass spectrometry is a part of this category, as well as the way valence electrons affect chemical reactions. Reactivity is a huge part of not only category 4D but of the CPBS section’s chemistry questions overall. The AAMC doesn’t provide percentage breakdowns of how prevalent each of these categories are in a given exam section, but historically quite a few of the discrete questions in the CPBS section will involve the use of reactivity principles and mass spectrometry. Although physics is obviously a part of the points covered in the Electronic Structure subtopic, virtually every other aspect of 4E is rooted in general chemistry. Even basics like atomic number and stoichiometry must be an important part of your studying and review. It’s also a good reminder that what you learn in your intro-level courses is extremely vital to scoring well throughout the MCAT. Atomic Nucleus Electronic Structure The Periodic Table - Classification of Elements into Groups by Electronic Structure Stoichiometry
Foundational Concept 5
FC5 is all about the way the micro affects the macro. Chemical principles at the atomic and subatomic level form the basis for the scientific understanding of “the molecular dynamics of living systems.” Moreover, this will demand understanding the role of chemical processes in shaping various frameworks including thermodynamics, intermolecular interactions, molecular dynamics and reactivity, and, of course, molecular structure. Using the categories elaborated below, the MCAT will ask students to utilize these core principles to answer questions relating to molecular and cellular functions in human health and disease.
The categories included in this foundational concept form the central pillar of chemistry knowledge tested on the MCAT, and makes up the majority of questions in the CPBS section. In reviewing these categories, make note of their presence in whatever study materials you have so far. Although much of it is general chemistry, and so should at least be familiar, some of the biochemistry-focused subcategories may require seeking out more specialized study materials to offset any gaps in your prior coursework.
Like Foundational Concept 4, FC5 is organized into 5 content categories.
The AAMC summarizes this category quite simply: the “unique nature of water and its solutions.” Given that water is extremely prevalent throughout the human body, the MCAT necessarily seeks to test students’ understanding of the role of water in processes like chemical interactions, ionization and mobilization of solutes, and energy absorption. Additionally, with the prevalence of general chemistry in this section, you’ll also be tested on basics like solutions and solubility, acids, bases, and buffers. 5A therefore tests knowledge in both general and biochemistry. Acid/Base Equilibria Ions in Solutions Solubility Titration On the bright side, if you’ve recently taken your introductory gen. chem or biochemistry courses much of this material will be fresh in your mind, and may not need a lot of review. You won’t know for sure until you take a full-length diagnostic test of course, but if much of this category seems familiar and well-trodden you’re in good shape. Another general chemistry-heavy category, 5B focuses on the nature of molecular and intermolecular interactions. Bond polarity, electrostatic principles, and even basic quantum mechanics will be a part of questions pulling from this category. As you can see, 5B will ask you to utilize extensive knowledge of molecular bonding, so making sure your organic chemistry review materials cover the topics below is crucial to equipping yourself properly. Covalent Bond Liquid Phase - Intermolecular Forces This category consists of one central topic: separations and purifications. Analysis of mixtures is heavily dependent on understanding various processes of separation and purification. Questions pulling from this category demand an understanding that particular methods of separation and purification are required depending on the substances involved in a mixture, and that these methods rely on determining the strengths of intermolecular interactions. As such, 5C is rooted in both organic and biochemistry, with questions requiring a thorough understanding of analytical methodology and technology. Notes from laboratory portions of your introductory chemistry courses will be especially helpful in reviewing the material in this category. Its topics include: 5D focuses on biological molecules and the mechanisms that control their various modes of reactivity. As the scope of this category is firmly within the realm of biological organisms and systems, review will focus on both biochemistry and organic chemistry, including the function and interactions of lipids, carbohydrates, alcohols, and much more. Topics within this category include: Nucleotides and Nucleic Acids Amino Acids, Peptides, Proteins The Three-Dimensional Protein Structure Non-Enzymatic Protein Function Lipids Carbohydrates Aldehydes and Ketones Alcohols Carboxylic Acids Acid Derivatives, including anhydrides, amides, and esters Phenols The final category within Foundational Concept 5 relates to chemical thermodynamics and kinetics. Fortunately, the depth of knowledge tested in these categories is not as significant as the general and organic chemistry topics of 5D, but there is a tremendous amount of multidimensionality—that is, questions pulling from this category will involve navigation of biochemistry, general chemistry, and physics, often within a single question or passage. Put another way, questions from this category will be dynamic just as their topics are dynamic, involving the ways in which the relative energies of products and reactants affect chemical equilibrium. Crucially, this will again largely be contextualized within biological systems, so questions involve navigating these biochemical and dynamic processes in relation to enzymatic functions and the conditions required to sustain them. Topics in this category include: Enzymes Principles of Bioenergetics Energy Changes in Chemical Reactions – Thermochemistry, Thermodynamics Rate Processes in Chemical Reactions - Kinetics and Equilibrium
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FAQs
1. What kind of chemistry questions are on the MCAT?
The three general categories of chemistry knowledge tested on the MCAT are general chemistry, biochemistry, and organic chemistry. There’s a lot of specific subtopics within those general categories, but the vast majority of chemistry questions will pull from general and biochemistry, so making sure you have a firm grasp of the foundations in these subfields will be very important as you study.
2. What is a good MCAT score?
Our answer to this is always “the best score your can achieve.” If you have your heart set on a specific school with a specific MCAT cutoff, then that certainly gives you a more concrete number to aim for, but you shouldn’t focus your studying on that specific number, no matter how much you may want to attend that particular medical school. Remember, there are some schools that don’t require the MCAT at all, so in the very worst case scenario of totally bombing the mcat in multiple retests, you can still get into a stellar MD program without the MCAT.
3. How do I get faster with passage-based questions?
Oddly enough, aspects of CARS strategy can be of great help in this regard, even with chemistry passages. Active reading for any passage-based question is crucial—you should be able to approach a passage with questions in mind such as “what is the topic of this passage?” as well as summarizing more unwieldy sentences for better comprehension. Similarly, reading challenging material throughout your test preparation will sharpen and quicken your analytical abilities, even on scientific passages. Basically, the better you are at reading and thinking while reading, the better you’ll do on all passage-based questions on test day.
4. Is it better to use difficult practice questions and tests?
Yes and no. There’s a place for really challenging practice questions and subject exams, but for diagnostic purposes, it’s always preferable to use practice exams that match the actual MCAT as closely as possible. You want as accurate a gauge of your abilities as possible at the outset and at the midway point, so attempting material that’s designed to exceed the difficulty of the actual exam will likely only result in discouragement. Certainly include intentionally difficult calculations and passages throughout your study sessions, but in moderation. You’re taking the MCAT, after all, not the USMLE Step-2.
5. How long is the Chemical and Physical Foundations of Biological Systems section of the MCAT?
Like the 3 other science-based sections of the MCAT, the CPBS section is comprised of 59 questions, for which you’ll be given 95 minutes to complete. The vast majority of the questions in this section will be passage-based, so a fair bit of your time will be spent reading and analyzing text. Improving your reading skills and speed—without rushing!—is key to performing well on this section.
6. I haven’t had any coursework in organic chemistry. How can I study for this section?
In short, you’ll simply need more time. The good news is that the MCAT is “a mile wide and an inch deep,” so you can focus on developing a breadth of general or foundational knowledge without getting too granular about any one aspect of organic chemistry. Ideally, if you have time, take a summer course in whatever prerequisites you haven’t completed, but barring that you can always seek out the textbooks from these classes and very carefully work through them. In this case, though, reaching out to an MCAT tutor or prep service will likely be the most effective and time-efficient option since they will be able to tailor a study plan for your very specific needs.
7. How hard is the MCAT?
The simple truth is that if the MCAT wasn’t challenging there’d be a lot more schools with 525 MCAT cutoffs. It’s hard! Just because it’s only an inch deep doesn’t mean you can’t drown in it. But this is exactly why MCAT study plans recommend an ideal 6-month prep period, and this number isn’t arrived at arbitrarily. Students have been taking the MCAT for decades now, and the strategies and best practices that good study guides and services recommend will help you improve your score if followed faithfully. No one, even the AAMC, wants to see students fail. If you invest significant time and energy into a well thought-out plan, you’ll do well. Don’t let the MCAT’s marathon-like nature scare you: in the end, it’s just one question after another, and if you’ve prepared well you’ll be fine.
8. How many times can I retake the MCAT if I do poorly?
The first thing to consider is whether or not that initial “poor” score is really the wet blanket it seems like. Again, if you need a specific score for a specific school, and you refuse to consider another, then you may want to retake the MCAT. Retesting is a serious and potentially disastrous decision though—unless you can guarantee a better score in a retest, it’s almost assuredly better to accept what you have and augment your plans to fit it. If you absolutely must retest though, you can retake the MCAT up to 3 times in a given testing year, 4 times in a 2-year period, and up to 7 times total in your lifetime.