AP Chemistry reference tables: What's given, what to expect, and how to work with them under time pressure

The AP (Advanced Placement) Chemistry reference packet is a three-page document you get for both Section I (multiple-choice) and Section II (free-response). It's the same document in both sections, and identical between the 2025 and 2026 exams. Knowing what's on it and how it's organized saves you time in the exam and stops you looking for information that isn't there.

This guide walks through each page, what it covers, and the three most common time-wasting habits students fall into when working with it. If you want each equation or constant explained in context, our companion pieces on the AP Chemistry equation sheet, AP Chemistry formula sheet, and the AP Chemistry periodic table go deeper into each page. Cognito's AP Chemistry course has topic-grouped lessons that reference the same tables you'll see on exam day.

Standard block layout, 7 periods across, 18 groups (1-18) labeled. All 118 elements shown. For each element you get:

Symbol at the top of each cell. Atomic number in one corner. Atomic mass, rounded to two or three decimal places, in the other.

What isn't on the table: Electronegativity values, atomic radii, ionization energies, electron configurations, the metalloid staircase, standard state labels (solid, liquid, gas), or any color coding. All of that is expected knowledge or given in the question when needed.

The periodic table is the page you'll reach for most. Use it for molar mass calculations, ion charge prediction from group number, and rapid trend ranking (radius, electronegativity, ionization energy). Most trend questions can be answered by pointing at four elements on the table and applying "increases up and to the right" or the opposite.

The equations page is organized into six clearly labeled sections:

Atomic structure and light – E = hν, c = λν, E = hc/λ. Used in photoelectron spectroscopy and hydrogen spectrum questions.

Equilibrium – General Kc, Kp, Ka, Kb, Kw expressions; pH, pOH, pKa, pKb definitions; and the Henderson-Hasselbalch equation (pH = pKa + log([A-]/[HA])). Used in every equilibrium and acid-base question. The Kp = Kc(RT)^Δn conversion isn't printed here – you memorise it.

Kinetics – General rate law form (Rate = k[A]^m[B]^n), integrated rate laws for first and second order, first-order half-life. Used in every kinetics question. The Arrhenius equation (k = A e^(-Ea/RT)) isn't on the sheet – memorise it for any activation-energy or two-temperature question.

Gases and solutions – Ideal gas law (PV = nRT), Dalton's law of partial pressures, molarity, dilution (M1V1 = M2V2). Used in every gas or solution problem.

Thermodynamics – q = mcΔT, ΔH from standard enthalpies of formation, ΔS from standard entropies, ΔG = ΔH - TΔS, ΔG = -RT ln K. Used in thermochemistry and thermodynamics questions.

Electrochemistry – ΔG° = -nFE°, I = q/t (linking current, charge, and time for electrolysis). Used in electrochemistry FRQs. The Nernst equation and specific standard reduction potentials aren't printed here – you memorise Nernst, and any E° values are given in the question stem.

The layout means you can navigate to the right block by unit. Kinetics question, look at the kinetics block. Thermo question, thermo block. This is quicker than skimming the whole page for a specific equation. The AP Chemistry units guide covers all 9 course units and shows which equations matter most for each.

Understanding what isn't included matters as much as knowing what is. If you spend the exam looking for information that isn't there, you burn time you don't have.

Standard reduction potentials for specific half-reactions aren't listed. If a question needs the E value for Cu2+ + 2e- reacts to form Cu, it will be given in the question stem or in an appended table.

Standard enthalpies of formation (ΔHf) and standard entropies (S) for specific substances aren't listed. Same rule – the question provides them if they're needed.

Ka, Kb, and Ksp values for specific acids, bases, and salts aren't listed. Same rule.

Bond enthalpies aren't listed. Same rule.

Solubility rules aren't provided. These are expected knowledge – Group 1 salts soluble, nitrates soluble, most sulfates soluble except with Pb, Ba, Ca, Sr, most hydroxides insoluble except with Group 1 and heavier Group 2, most carbonates and phosphates insoluble.

Common polyatomic ions and their charges aren't provided. Nitrate, sulfate, phosphate, carbonate, hydroxide, ammonium, and acetate are examinable and expected.

Habit 1: Skimming the whole equation page every time you need a formula. The page is organized by topic. Kinetics questions send you to the kinetics block, not the whole page. Build the mental map of which block goes with which unit during revision, not during the exam.

Habit 2: Hunting the sheet for information that's in the question. If a question gives you Ka = 1.8 x 10^-5 for acetic acid, don't scan the sheet for a Ka table. There isn't one. The number you need is right in front of you.

Habit 3: Ignoring units on constants. R comes in three flavors on the sheet; picking the wrong one is a very common source of wrong answers on gas problems and thermodynamics problems. Read the units in the question first, then pick the matching constant.

The reference packet is designed to reduce memorization, not eliminate reasoning. A student who uses it fluently – reaching for the right equation without hesitation, matching R to the units in front of them, ignoring the sheet when the answer is expected knowledge – has a real advantage over a student who treats it as a lookup crutch.

The cleanest way to build fluency is timed past-paper practice with the sheet open, so that using it becomes automatic. Cognito's AP Chemistry course organizes lessons and questions unit by unit, and the wider AP course catalog offers the same structure for the other AP sciences and social sciences. Our study guide for AP Chemistry provides a three-month study plan built around timed practice.