AP sciences and calculus · 39 cards · sources listed below

AP Chemistry flashcards for all nine units

This starter set collects ideas and relationships that come up across the nine units of AP Chemistry: trends, models, rate laws, equilibrium and thermodynamic relationships. It is an independent study aid, not affiliated with the College Board. It is a core-concept set, not a replacement for working problems.

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Free AP Chemistry flashcards: 39-card starter set

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Units 1-2: Atomic Structure and Compound Structure (9)

State Coulomb's law in words and why it explains periodic trends.

The force between charges is proportional to the product of the charges and inversely proportional to the square of the distance between them. Larger effective nuclear charge and smaller distance mean stronger attraction to electrons.

First ionization energy: trend across a period and down a group

It generally increases across a period (greater effective nuclear charge, smaller radius) and decreases down a group (electrons farther from the nucleus and more shielded).

Why is the first ionization energy of Al lower than Mg, and O lower than N?

Al: its 3p electron is higher in energy and shielded by the 3s electrons. O: paired electrons in a p orbital repel each other, making one easier to remove.

Which two ground-state electron configurations are common exceptions?

Chromium is [Ar] 4s1 3d5 and copper is [Ar] 4s1 3d10, because half-filled and filled d subshells are more stable.

How do you read a photoelectron spectrum?

Peak position (binding energy) tells you the subshell, and peak height tells you the number of electrons in it.

Describe ionic, covalent and metallic bonding.

Ionic: electrostatic attraction between cations and anions. Covalent: shared electron pairs between nonmetals. Metallic: cations in a sea of delocalized electrons, which explains conductivity and malleability.

Why can electron-domain geometry differ from molecular geometry?

Lone pairs count as electron domains but are not atoms. NH3 has four domains (tetrahedral) but is trigonal pyramidal; H2O has four domains but is bent.

Match electron domains with hybridization.

Two domains: sp (linear). Three: sp2 (trigonal planar). Four: sp3 (tetrahedral).

How many sigma and pi bonds are in single, double and triple bonds?

Single: one sigma. Double: one sigma and one pi. Triple: one sigma and two pi.

Unit 3: Intermolecular Forces, Gases, Solutions and Light (8)

Rank the types of intermolecular forces by general strength.

London dispersion forces are weakest in small molecules, then dipole-dipole, then hydrogen bonding. Ion-dipole forces are stronger still. Dispersion forces grow with the number of electrons.

What is needed for hydrogen bonding?

A hydrogen atom bonded to N, O or F, attracted to a lone pair on a nearby N, O or F atom.

State the ideal gas law.

PV = nRT. Temperature must be in kelvin; R = 0.0821 L atm/(mol K) or 8.314 J/(mol K).

Kinetic molecular theory: what does temperature measure?

The average kinetic energy of the particles is proportional to the absolute (kelvin) temperature.

Dalton's law of partial pressures

Total pressure is the sum of partial pressures. Partial pressure of a gas = its mole fraction x total pressure.

When do real gases deviate most from ideal behavior?

At high pressure and low temperature, when particle volume and intermolecular attractions matter.

Define molarity.

Moles of solute per liter of solution (M = mol/L).

State the Beer-Lambert law.

A = abc (absorbance = molar absorptivity x path length x concentration). Absorbance is proportional to concentration.

Units 4-6: Chemical Reactions, Kinetics and Thermochemistry (11)

How do you write a net ionic equation?

Write the balanced complete ionic equation and remove spectator ions that appear unchanged on both sides.

Percent yield formula

Percent yield = (actual yield / theoretical yield) x 100.

Define oxidation and reduction in terms of electrons.

Oxidation is loss of electrons (oxidation number increases). Reduction is gain of electrons (oxidation number decreases).

Can you read reaction order from the balanced equation?

No. Rate = k[A]^m[B]^n, and the orders m and n are found experimentally, for example from initial-rate data.

What graph is linear for zero, first and second order reactions?

Zero order: [A] vs t. First order: ln[A] vs t. Second order: 1/[A] vs t.

What is the half-life of a first-order reaction?

t1/2 = 0.693/k, independent of the initial concentration.

How does a catalyst work, and what does it not change?

It provides a pathway with lower activation energy, so the rate increases. It does not change delta H or the equilibrium constant.

In a multistep mechanism, what sets the rate law?

The slowest (rate-determining) step. Intermediates are made then consumed; catalysts are consumed then regenerated.

Heat equation for a temperature change

q = mc(delta T), with q in joules, m in grams, c specific heat.

State Hess's law.

The enthalpy change for a reaction equals the sum of enthalpy changes for the steps it can be divided into. Reverse a step and its sign flips; multiply a step and delta H scales.

Estimating reaction enthalpy from bond energies

delta H = energy of bonds broken - energy of bonds formed (breaking bonds takes energy).

Units 7-9: Equilibrium, Acids and Bases, Thermodynamics, Electrochemistry (11)

How do you use Q and K to predict direction?

If Q < K, the reaction shifts toward products. If Q > K, it shifts toward reactants. If Q = K, it is at equilibrium.

What is the only change that alters the value of K?

A change in temperature. Concentration, pressure and catalysts change the position or rate, not K.

Which species appear in an equilibrium expression?

Gases and aqueous species. Pure solids and pure liquids are left out.

What does the common ion effect do to solubility?

Adding an ion already in the dissolution equilibrium shifts it toward the solid and lowers the solubility of the salt.

Key relationships for pH

pH = -log[H+]; pH + pOH = 14 and Kw = [H+][OH-] = 1.0 x 10^-14 at 25 C; Ka x Kb = Kw for a conjugate pair.

Henderson-Hasselbalch equation and what a buffer contains

pH = pKa + log([A-]/[HA]). A buffer has a weak acid and its conjugate base in comparable amounts. At the half-equivalence point of a weak acid titration, pH = pKa.

Is the pH at the equivalence point of a weak acid with a strong base above or below 7?

Above 7, because the conjugate base of the weak acid hydrolyzes to make OH-.

Relate delta G to delta H, delta S and spontaneity.

delta G = delta H - T delta S. A reaction is thermodynamically favorable when delta G is negative.

Link delta G standard to K and to cell potential.

delta G standard = -RT ln K and delta G standard = -nF E standard.

Galvanic vs electrolytic cells

Galvanic: spontaneous, E cell positive, converts chemical energy to electrical energy. Electrolytic: needs external energy. In both, oxidation happens at the anode and reduction at the cathode.

Nernst equation

E = E standard - (RT/nF) ln Q. As Q increases, cell potential decreases; E = 0 at equilibrium.

What this set covers

Course units covered

All 9: Atomic Structure and Properties; Compound Structure and Properties; Properties of Substances and Mixtures; Chemical Reactions; Kinetics; Thermochemistry; Equilibrium; Acids and Bases; Thermodynamics and Electrochemistry.

Best used for

Memorising definitions, trends and relationships so you can spend problem-solving time on setup, not recall.

Not covered

Worked calculations, lab procedure and data analysis, and the full set of constants. Practise those separately and add cards for your errors.

How to study this set

Chemistry cards work best for relationships and definitions. Pair them with problem sets so recall turns into setup.

1
Day 1
Study one unit group. Write each equation from memory and say what every symbol and unit means.
2
Days 2-7
Review the day's missed cards, then do five problems that use those relationships. Add a card for any step you got wrong.
3
Week 2
Mix units. Explain trends and anomalies aloud in terms of Coulomb's law and particle-level pictures, as free-response questions ask.
4
Final week
Quiz yourself on sign conventions and direction-of-shift questions (Q vs K, delta G, E cell), the usual places to lose points.

Spaced repetition schedules each card to come back just before you would forget it, so reviews get shorter as your recall gets stronger. Cards you miss come back sooner.

Common mistakes to avoid

Explaining trends without Coulomb's law

Answers like "it is farther from the nucleus" earn more when they name the electrostatic attraction, effective nuclear charge and shielding.

Using stoichiometric coefficients as reaction orders

Rate law orders come from experiment or the slow step of a mechanism, not from the balanced equation.

Forgetting units and kelvin

Gas law and thermodynamics problems need kelvin, and delta S is usually in J/(mol K) while delta H is in kJ/mol.

Mixing up what changes K

Only temperature changes K. Concentration or pressure changes change Q and shift the position of equilibrium.

Make your own from your notes

A starter set is a head start, not your whole course. Your class notes, slides and textbook are what your teacher actually tests, so turn them into cards too.

Make "when do I use it?" cards: front describes a problem type, back names the equation and what to check (units, kelvin, sign).
Copy explanations that earned points on free-response questions and turn each into a cause-and-effect card.
Avoid cards that need a big calculation; keep the calculation in practice problems and put the setup on the card.
Generate cards from lab write-ups: front the observation, back the particle-level explanation.

Generate cards from a topic or notes Turn a PDF into flashcards

AP Chemistry flashcards: questions

Do I need to memorise equations for AP Chemistry?

The College Board has provided an equations and constants sheet with the exam, so concentrate on understanding what each equation means and when to use it. Check the current exam instructions on AP Central to confirm what you will be given.

What is the best way to study kinetics and equilibrium?

Make relationship cards, then work through problems that ask for direction of change. Practise explaining in words what happens at the particle level.

How is thermochemistry different from thermodynamics in the course?

Thermochemistry (Unit 6) deals with heat flow, calorimetry and enthalpy. Thermodynamics (Unit 9) adds entropy, free energy and the link to equilibrium and cell potential.

Can I use these cards for a college general chemistry course?

Many of the ideas overlap, but your course may be organised differently. Add cards for any topics your syllabus emphasises.

Are these official College Board materials?

No. They are an independent study aid whose grouping follows the published course units.

Sources and review

These cards are an independent study aid, not official exam content, and are not affiliated with or endorsed by any exam body or publisher. They were written by hand and checked against the sources below on 2026-10-17. Always confirm details with your course materials and the current official documents.

College Board: AP Chemistry course page — Checked the names and order of the nine units used for grouping; individual cards written from standard course content.
OpenStax: Chemistry 2e — Open textbook used as a general reference for the standard chemistry relationships on the cards.

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