AP Chemistry Complete Review and Exam Guide 2027
Prepare by representation, calculation, and evidence
AP Chemistry · Complete ReviewAP Chemistry Complete Review and Exam Guide 2027
- 58-page review
- 9 units
- 60 MCQs · 7 FRQs
AP Chemistry asks you to move among particle diagrams, equations, graphs, numerical data, and laboratory evidence. The exam lasts 3 hours and 15 minutes: 60 multiple-choice questions in 90 minutes and 7 free-response questions in 105 minutes, with each section worth 50% of the score.
- How AP Chemistry is assessed Both sections recommend a scientific or graphing calculator; the free-response section contains 3 long and 4 short questions.
- How to use the review Name the requested quantity or claim, choose evidence that answers it, show units and signs, and check the result against the chemical model.
- Reference-sheet readiness Practice choosing relationships from the provided equations and constants sheet while memorizing common ion formulas, solubility rules, and other facts that are not printed there.
- Independent practice Worked numbers, settings, and explanations are written for this guide rather than copied from official questions.
What AP Chemistry covers
The course has nine units in the order shown below. Each percentage is a published range for multiple-choice content, not a promised question count and not a free-response quota.
AP Chemistry timing, questions, and calculator use
The two sections have equal score weight. Calculator guidance is stated separately for each section so your practice setup matches the task you are doing.
| Total testing time | 3 hours and 15 minutes |
|---|---|
| Section I · Multiple Choice | 60 questions · 90 minutes · 50% of the exam score · scientific or graphing calculator recommended for this section |
| Section II · Free Response | 7 questions · 105 minutes · 50% of the exam score · scientific or graphing calculator recommended for this section |
| Free-response mix | 3 long questions (10 points each) and 4 short questions (4 points each) |
Check current exam details at College Board — AP Chemistry exam. Official information shown here is current as of 2026-08-29.
Read a spectrum and preserve the electron count
Read each question as it appears on the exam paper, choose your answer, then tap it to see the feedback.
Element Q has atomic number 24. A Q³⁺ ion is analyzed, and an isotope spectrum has peaks at mass numbers 50, 52, and 53 with relative abundances 10.0%, 80.0%, and 10.0%.
Write the ground-state electron configuration of Q³⁺, identify the most abundant isotope, and explain what distinguishes the mass-53 isotope from mass-52.
Show your work.
A. Q³⁺ is [Ar] 3d³; mass 52 is most abundant; mass 53 has one more neutron than mass 52.
✅ Correct! 😊 Correct. Removing three electrons gives 21 electrons, the 80.0% peak identifies mass 52, and equal proton counts make the one-mass-number difference a neutron difference.
B. Q³⁺ is [Ar] 3d⁶; mass 52 is most abundant; mass 53 has one more proton.
❌ Not quite 😭 This adds electrons to form a positive ion and changes the proton count between isotopes. Both moves break the particle-count evidence.
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C. Q³⁺ is [Ar] 3d³; mass 53 is most abundant; mass 53 has one more neutron.
❌ Not quite 😭 The configuration and isotope comparison are sound, but peak position does not determine abundance. The tallest, 80.0% peak is mass 52.
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D. Q³⁺ is [Ar] 3d²4s¹; mass 52 is most abundant; mass 53 has one more electron.
❌ Not quite 😭 Electrons are removed from 4s before 3d, and isotopes differ in neutrons rather than electrons. This answer misuses two distinct representations.
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Full explanation
- Step 1Neutral Q has 24 electrons, so Q³⁺ has 24 − 3 = 21 electrons.
- Step 2From [Ar] 3d⁵4s¹, remove the 4s electron first and then two 3d electrons to obtain [Ar] 3d³.
- Step 3The 80.0% signal makes mass 52 the most abundant isotope.
- Step 4Both isotopes have 24 protons; mass 53 therefore has one more neutron than mass 52.
A student compares two colorless aqueous samples using particle diagrams and conductivity data.
Which observation best supports the claim that one sample contains a greater concentration of mobile ions?
Select the best answer.
A. The sample produces the larger conductivity reading under the same conditions.
✅ Correct! 😊 Correct. With conditions controlled, greater conductivity directly supports a greater concentration of mobile charged particles.
B. The sample occupies the larger container.
❌ Not quite 😭 Container size alone does not establish ion concentration. Amount and volume must be related, not considered separately.
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C. The sample has the higher liquid level.
❌ Not quite 😭 A higher liquid level indicates more volume in that container, not necessarily more ions per volume.
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D. The sample's particles are drawn larger.
❌ Not quite 😭 Symbol size in a particle diagram is not a concentration measurement unless the key explicitly defines it that way.
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Full explanation
- Step 1Identify the requested claim: concentration of mobile ions.
- Step 2Look for evidence that responds to charged particles rather than total liquid volume or drawing style.
- Step 3Compare measurements only under the same experimental conditions.
- Step 4Conductivity is the direct supporting observation among the choices.
Fifteen AP Chemistry terms with definitions
These fifteen definitions are selected from the review appendix. Use each term as an instruction about what evidence to read or what feature to show, not as an isolated flash-card label.
- atomic number
- The proton count that fixes an element's identity.
- isotope
- An atom of the same element with a different neutron count.
- mass spectrum
- A display whose signal positions and relative intensities reveal mass-to-charge values and abundance.
- electron configuration
- A notation showing how an atom or ion's electrons occupy subshells.
- valence electron
- An electron in the outer occupied energy levels that commonly participates in bonding or ion formation.
- effective nuclear charge
- The net attractive influence an electron experiences after shielding is considered.
- shielding
- Reduction of nucleus–electron attraction caused by other electrons between them.
- ionization energy
- Energy required to remove an electron from a gaseous atom or ion under the stated step.
- atomic radius
- A measure of atomic size inferred from a defined internuclear distance or model.
- Lewis structure
- A bonding model that displays bonds and nonbonding valence electrons.
- formal charge
- An electron-bookkeeping value used to compare plausible bonding contributors.
- resonance
- Use of multiple electron placements with the same atom skeleton to describe delocalization.
- electron domain
- One bonding region or lone-pair region around a central atom.
- molecular geometry
- The arrangement of bonded atoms around a selected center, excluding lone pairs from the shape name.
- London dispersion
- Attraction arising from temporary, correlated fluctuations in electron clouds.
AP Chemistry FAQ
How is the AP Chemistry exam divided?
The exam lasts 3 hours and 15 minutes. The 60-question multiple-choice section lasts 90 minutes and counts for 50%; the 7-question free-response section lasts 105 minutes and counts for 50%.
What calculator should a student use?
A scientific or graphing calculator is recommended for both sections.
Are equations and constants provided?
Yes. The exam provides an equations and constants reference; students still need to choose the correct relationship and know chemical facts not listed there.
Are the practice numbers copied from published questions?
No. Practice settings and numerical values in this guide are independently written and labeled as illustrative.
What must I memorize if the exam provides equations and constants?
The exam provides an equations and constants sheet, but it does not list every fact you need. Memorize common ion formulas, solubility rules, and other required chemical facts that are not printed on the sheet.
Are the multiple-choice questions in this review official released questions?
No. The public materials available for this review do not include officially released multiple-choice questions. The multiple-choice format page explains the official framework with independently written examples; it is not a collection of official questions.
How to study for AP Chemistry
Read each worked page in three passes. First identify the requested particle, quantity, graph feature, or explanation. Next reproduce the calculation or reasoning with units and signs visible. Finally audit every row of the four-column scoring check.
Translate before calculating. Move deliberately among particulate, symbolic, graphical, and macroscopic evidence. Write what each axis, coefficient, concentration, charge, or temperature measures before selecting an equation.
Use weight ranges to schedule practice, not to predict the test. Give Properties of Substances and Mixtures and Acids and Bases longer review blocks, then keep all seven 7-9% units active in mixed sets. Published ranges never guarantee a fixed item count.
Practice with and without the reference sheet. With the sheet open, find the correct relationship quickly and state its assumptions. With it closed, recall common ions, solubility rules, particle conventions, and the chemical facts the sheet does not supply.
