The periodic table is the first page of your AP (Advanced Placement) Chemistry reference packet. You get it in both the multiple-choice and free-response sections, and the same version has been used for the 2025 and 2026 exams. It's a plain table – element symbols, atomic numbers, and atomic masses, laid out in the usual block form. No electronegativity, no atomic radii, no ionization energies printed on it.
That's the whole point. The exam expects you to know the trends and reason from position, not read numbers off. This guide walks through what's on the table, what isn't, and the specific ways it saves you time in the exam. For the full course context and practice, Cognito's AP Chemistry lessons build every trend from the periodic table itself.
What's on the AP Chemistry periodic table
Every element from hydrogen (Z = 1) to oganesson (Z = 118) is on the table, arranged in the standard block layout: 18 groups across, 7 periods down, with the lanthanides and actinides separated below. For each element you get three things:
Element symbol (e.g., Fe for iron), atomic number in the top corner (Fe is 26), and atomic mass rounded to a few decimal places (Fe is 55.85).
That's it. No colors coding metals versus nonmetals, no electron configurations, no melting points, no bond enthalpies. The metalloid staircase between B, Si, Ge, As, Sb, Te isn't drawn on. The distinction between s-block, p-block, d-block, and f-block isn't visually marked either.
Students who've studied from colorful textbooks sometimes reach for the exam sheet expecting more, then lose a few seconds realizing the information they wanted isn't there. Know what to expect before test day.
The atomic masses on the AP table are the ones you use for molar mass calculations. Don't use a rounded 12 for carbon in an FRQ – use the printed 12.01. The rubrics build in tolerance, but consistent use of the printed values keeps you inside it.
Trends you have to know from the position
The periodic table on the sheet is useful mostly because you can point at it and reason about trends without the exam giving you the numbers. Five trends come up over and over.
Atomic radius increases down a group (more electron shells) and decreases across a period (higher nuclear charge pulling electrons in). So Cs is bigger than Na, and F is smaller than Li.
Ionization energy does the opposite: Decreases down a group (outer electrons farther from the nucleus, easier to remove) and increases across a period (stronger effective nuclear charge). Cs has a low first ionization energy; He has the highest of any element.
Electronegativity follows the same pattern as ionization energy – decreases down a group, increases across a period. Fluorine is the most electronegative element on the table; francium is the least.
Metallic character is the opposite of electronegativity. Increases down and to the left, decreases up and to the right. The staircase between metals and nonmetals runs from B down to At.
Effective nuclear charge (Zeff) increases across a period as protons pile up without much added shielding. This is the underlying cause of the electronegativity and ionization energy trends, and questions often ask you to explain a trend using Zeff, not just to state it.
How to use the table on multiple-choice questions
Several MCQ (multiple-choice question) patterns rely on reading the table quickly.
Ranking questions ask you to put elements or ions in order of atomic radius, ionization energy, or electronegativity. Rather than trying to remember specific values, locate all four elements on the table and apply the trends. Elements higher and to the right are usually smaller and more electronegative.
Oxidation state predictions get easier when you use group number. Group 1 elements form +1 ions, Group 2 form +2, Group 13 form +3, Group 15 form -3, Group 16 form -2, Group 17 form -1. Transition metals are more variable, but common charges (Fe as +2 or +3, Cu as +1 or +2) are expected knowledge.
Molar mass calculations for stoichiometry are done directly from the table. Water is 2(1.01) + 16.00 = 18.02 grams per mole. Copper(II) sulfate pentahydrate (CuSO4 5H2O) works out to 63.55 + 32.07 + 4(16.00) + 5(18.02) = 249.72 grams per mole, all from atomic masses on the sheet.
Electron configuration prediction from position: Group and period tell you the outermost subshell. Sulfur is in period 3, group 16, so its valence is 3s^2 3p^4. Iron is in period 4, group 8 (in the d-block), so its configuration ends in 3d^6 4s^2 (or [Ar] 3d^6 4s^2).
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How to use the table on free-response questions
FRQ (free-response question) answers reward you for explicit reasoning from the table. Two examples.
On a photoelectron spectroscopy question asking why the first ionization energy of oxygen is lower than nitrogen despite oxygen having more protons, you're expected to say that oxygen's fourth 2p electron pairs up in an orbital, and pairing repulsion makes it easier to remove. The periodic table gives you the positions; you supply the reasoning.
On an electron affinity or Lewis structure question, you use group number to know how many valence electrons each atom brings. Nitrogen (group 15) brings 5, oxygen (group 16) brings 6, chlorine (group 17) brings 7. For a molecule like NClO2, count each atom once: N (5) + Cl (7) + 2 O (12) = 24 valence electrons. Miscounting at the start makes the whole Lewis structure wrong.
On thermodynamics questions that ask you to justify why a certain reaction has a positive or negative entropy change, position on the table can help you spot changes in state or increases in the number of gas moles, both of which come from knowing which elements are gases at room temperature (H, N, O, F, Cl, and the noble gases).
Circle the elements you need at the start of a long FRQ. Locating four elements once and marking them saves the repeated eye-flicks between the question and the table across a five-part question. Small time savings across a 105-minute section add up.
The parts of the table students underuse
Two areas of the table often get ignored until a question forces the issue.
The d-block (groups 3-12) shows up in electrochemistry FRQs and coordination chemistry questions. Being fluent with common transition metals – their common oxidation states, whether they form colored ions in solution, whether they're paramagnetic – pays off. Copper, iron, chromium, manganese, silver, and zinc appear most often.
The lanthanides and actinides (the f-block) show up rarely in AP Chemistry, but when they do (typically in a photoelectron spectroscopy context or a radioactive decay question in an introductory context), knowing that these are f-block elements and that their chemistry involves f orbitals is worth a mark or two.
Group 18 (noble gases) gets used mainly as a reference point in electron configurations ([Ar] as shorthand for the first 18 electrons) and as a comparison for stability arguments (why atoms form ions that reach a noble gas configuration).
Reading the table under time pressure
Ten minutes twice a week for the last month is enough to make the table feel automatic.
- Given an element symbol, name the group and period without looking (e.g., Br is group 17, period 4)
- Given a position, predict the valence electron count and common ion charge
- Rank three random elements by atomic radius, then by electronegativity, in under 15 seconds
- Calculate molar mass for five random compounds without a calculator (rounding to whole numbers is fine for the drill)
- Write the electron configuration for any element up to Kr from its position
- Identify whether two elements are in the same block (s, p, d, f) at a glance
Two extra habits worth building. First, always double-check atomic mass when you read from the table under stress. Iron (55.85) and cobalt (58.93) are adjacent, and misreading one for the other has ruined more than one FRQ. Second, note that the table wraps: Hydrogen is drawn above Group 1, but it isn't an alkali metal, and its chemistry looks more like Group 17 in some ways. Questions occasionally probe this.
If you want the trends taught in context alongside worked past-paper questions, Cognito's AP Chemistry course notes group them into a single unit on atomic properties. The full AP catalog covers the sciences and social sciences students most often pair with chemistry.
