HESI A2 Chemistry Review: What to Expect and How to Pass

Not every nursing school requires the HESI A2 Chemistry section — but if yours does, this guide covers exactly what's on it, how hard it really is, and the most efficient way to prepare, even if chemistry was never your strongest subject.

Is the HESI A2 Chemistry Section Hard?

The HESI A2 Chemistry section tests foundational, introductory-level chemistry — not advanced or organic chemistry. Most test-takers describe it as a "know it or you don't" section. If you took high school chemistry or a college general chemistry course, much of this will be review.

The section typically has 25 questions with a 25-minute time limit, giving you about one minute per question. Most are straightforward recall questions, not multi-step calculations.

What Topics Are Covered?

1. Atomic Structure

You must understand the parts of an atom: protons (positive, in nucleus), neutrons (neutral, in nucleus), and electrons (negative, in electron shells). Know how to determine each from the periodic table using atomic number and mass number.

2. The Periodic Table

Understand how the table is organized: periods (rows) and groups (columns). Know the trends — electronegativity increases left to right, atomic radius increases top to bottom. Be able to identify metals, nonmetals, and metalloids.

3. Chemical Bonds

• Ionic bonds: Transfer of electrons between a metal and nonmetal (e.g., NaCl)
• Covalent bonds: Sharing of electrons between nonmetals (e.g., H₂O)
• Hydrogen bonds: Weak bonds between molecules (important in water and DNA)

4. Chemical Reactions

Know the basic reaction types: synthesis (A + B → AB), decomposition (AB → A + B), single replacement, and double replacement. You should be able to balance simple chemical equations using the Law of Conservation of Mass.

5. Solutions and Concentrations

Understand solute (substance being dissolved), solvent (substance doing the dissolving), and solution (the mixture). Know what affects solubility: temperature, pressure, and the nature of the solute/solvent.

6. Acids, Bases, and pH

The pH scale runs from 0 (most acidic) to 14 (most basic), with 7 being neutral. Acids donate hydrogen ions (H⁺); bases accept them. Remember the scale is logarithmic — each whole number represents a tenfold difference.

7. States of Matter

Know the properties of solids, liquids, gases, and plasma. Understand phase transitions: melting, freezing, evaporation, condensation, sublimation, and deposition.

How to Study for HESI Chemistry Efficiently

1. Don't over-study. This is introductory chemistry. If you find yourself studying reaction kinetics or stoichiometry calculations, you've gone too deep.
2. Use flashcards for periodic table trends, bond types, and pH values of common substances.
3. Practice with timed quizzes to get comfortable with the 1-minute-per-question pace.
4. Watch YouTube videos on topics you're weakest in — visual explanations help chemistry concepts stick.

Frequently Asked Questions