What's in General Chemistry I: the 13 units in order
The 13 units of a first-semester general chemistry course, what each covers, how they map to OpenStax Chemistry 2e chapters 1-10, and the free Encodr deck.
General Chemistry I is the first semester of the two-course general chemistry sequence most science majors and pre-health students take. It starts with measurement and ends with liquids and solids, and almost every unit leans on the one before it. Encodr's free General Chemistry I course follows that order: 13 units, 61 chapters, 1,136 study cards plus 61 chapter notes, drawn from 33 cited sources. It maps to chapters 1-10 of OpenStax Chemistry 2e, the free textbook many intro courses use.
Here is what each unit covers and why it sits where it does.
Unit 1: Measurement and matter
Scientific method, classifying matter (elements, compounds, mixtures), physical versus chemical properties, SI units and metric prefixes, significant figures, accuracy versus precision, dimensional analysis and density. This is OpenStax chapter 1. Dimensional analysis looks trivial here and turns into the backbone of every calculation later, so it is worth doing by hand now.
Unit 2: Atoms and the periodic table
Early atomic theory (Dalton, Thomson, Rutherford), protons, neutrons and electrons, isotopes, average atomic mass and the layout of the periodic table: groups, periods, metals, nonmetals and metalloids. OpenStax chapter 2.
Unit 3: Compounds and nomenclature
Molecular versus ionic compounds, then naming: ionic compounds (including metals with more than one charge, like iron(II) and iron(III)), molecular compounds with Greek prefixes, and acids. Also OpenStax chapter 2. Naming is pure memorization, which makes it a good fit for flashcards and a bad fit for rereading.
Unit 4: The mole and composition
Avogadro's number (6.02214076 x 10^23 per mole, exact since the 2019 SI redefinition), molar mass, percent composition, empirical and molecular formulas, molarity and dilution, and other concentration units (mass percent, ppm, mole fraction). OpenStax chapter 3. The molar mass calculator and dilution calculator cover two of the core calculations here, and C1V1 = C2V2 explained walks through dilution problems.
Unit 5: Chemical reactions
Writing and balancing equations, precipitation reactions and the solubility rules, acid-base (neutralization) reactions, oxidation numbers and redox, and net ionic equations. The start of OpenStax chapter 4. OIL RIG (oxidation is loss, reduction is gain) is the one widely used mnemonic in this unit.
Unit 6: Stoichiometry
Mole ratios from a balanced equation, limiting reactant, theoretical and percent yield, titration and gravimetric analysis. The rest of OpenStax chapter 4. This is where units 4 and 5 come together, and it is the unit most students point to when they say chemistry "clicked" or didn't. Stoichiometry step by step works through the method.
Unit 7: Thermochemistry
Energy, heat and work, specific heat and calorimetry (q = mc delta T), enthalpy and thermochemical equations, Hess's law and standard enthalpies of formation. OpenStax chapter 5. Sign conventions are the main trap: an exothermic process has a negative q for the system.
Unit 8: Light and the quantum atom
Electromagnetic radiation (c = lambda nu), photons and the photoelectric effect (E = h nu), the Bohr model and atomic line spectra, wave-particle duality and the four quantum numbers. The first half of OpenStax chapter 6.
Unit 9: Electron configurations and periodic trends
The aufbau principle, the Pauli exclusion principle and Hund's rule, orbital diagrams and the common exceptions (chromium and copper), then periodic trends: atomic radius, ionization energy and electron affinity. The second half of OpenStax chapter 6. Trends are much easier once you tie them to configurations instead of memorizing arrows on a table.
Unit 10: Chemical bonding
Ionic bonding and lattice energy, covalent bonding and electronegativity, Lewis structures, formal charge and resonance, and bond strength and bond enthalpy. OpenStax chapter 7, sections 7.1 to 7.5.
Unit 11: Molecular shape and bonding theories
VSEPR geometries, molecular polarity, valence bond theory and hybridization, sigma and pi bonds, and molecular orbital theory. OpenStax section 7.6 plus chapter 8. VSEPR is the most tested topic here; molecular orbital theory at this level is mostly about bond order and whether a species is paramagnetic.
Unit 12: Gases
Pressure and its units, the simple gas laws (Boyle, Charles, Gay-Lussac, Avogadro), the ideal gas law, gas density, molar mass and gas stoichiometry, Dalton's law of partial pressures, effusion and Graham's law, and kinetic molecular theory. OpenStax chapter 9. The ideal gas law calculator handles the unit conversions, and the ideal gas law with worked examples covers the problem types.
Unit 13: Liquids and solids
Intermolecular forces (London dispersion, dipole-dipole, hydrogen bonding, ion-dipole), properties of liquids like viscosity, surface tension and vapor pressure, phase transitions and heating curves, phase diagrams, and types of solids and crystal lattices. OpenStax chapter 10.
How the course is built
Each chapter opens with a note card that holds the definitions and formulas the chapter's cards rely on. The course has no images, so every card can be answered in text. The cards mix question-and-answer, multiple choice, cloze (fill in the blank), typed numeric answers for the math, true/false and sequence cards for multi-step procedures like determining a VSEPR shape. Every typed calculation was recomputed independently before publishing, and the constants follow OpenStax and NIST: R = 0.08206 L atm/(mol K), 1 atm = 760 mmHg = 101.325 kPa, and STP as 273.15 K and 1 atm.
If your course uses a different textbook, the order may shift a little. Some courses teach thermochemistry after bonding, and some move gases earlier. The content is the same standard first-semester material, so you can study units in whatever order your syllabus uses.
What comes next
General Chemistry II picks up with solutions, kinetics, equilibrium, acids, bases and buffers, thermodynamics, electrochemistry and nuclear chemistry. See what's in General Chemistry II, and first-year science courses: biology, chemistry and physics for how the six intro science courses fit together. For study strategy, read how to study for a general chemistry exam. If you're taking biology the same term, the first units of General Biology I reuse this course's bonding and molecule material.
The General Chemistry I flashcards are free on Encodr, in this same unit order.
Encodr turns this into a habit: study anything in a feed, and it schedules the rest.
Get started free