AP Chem Unit 1: Moles and Molar Mass (2024 CED)

Not gonna lie, unit one of AP Chemistry is the hardest of the course if you have not already taken the prerequisite high school chemistry course. There are three options to design learning materials for this unit in AP Chem. First is to assume students have forgotten nothing from last year and have all the necessary prerequisite knowledge. The second is to find a textbook that covers all of the necessary materials. I have not been able to do othat yet. So… the last is to rearrange the first unit entirely because the college board progression is built assuming prerequisite knowledge is perfect.

Since I am making a learning/teaching resource, I am going to build this out the way I would teach it in the classroom rather than the textbook alignment or the College Board progression. But I am also leaving the College Board headings if you want to switch it up. Where some topics seem more difficult, I am adding additional resources, but you/your student may not need all of them.

If you have a good resource to add, please message me! Teaching is dynamic and “best” is so subjective that I really would value learner feedback and suggestions. But Jeremy Krug is the G.O.A.T. of AP Chem. So dont tell me otherwise. But all other comments and suggestions are welcomed!

Last Updated Feb 26, 2026 By SM.

T01.05 Atomic Structure and Electron Configuration

Learning Goals

  • 1.5.A.1 The atom is composed of negatively charged electrons and a positively charged nucleus that is made of protons and neutrons.
  • 1.5.A.3 In atoms and ions, the electrons can be thought of as being in ‘shells’ (energy levels) and ‘subshells’ (sublevels), as described by the ground-state electron configuration. Inner electrons are called core electrons, and outer electrons are called valence electrons.

Lessons & Activities

T01.07 Periodic Trends

Learning Goals

  • 1.7.A Explain the relationship between trends in atomic properties of elements and electronic structure and periodicity.
  • 1.7.A.1 The organization of the periodic table is based on patterns of recurring properties of the elements, which are explained by patterns of ground-state electron configurations and the presence of completely or partially filled shells (and subshells) of electrons in atoms.
  • 1.7.A.2.i Trends in atomic properties within the periodic table (periodicity) can be predicted by the position of the element on the periodic table and qualitatively understood using Coulomb’s law, the shell model, and the concepts of shielding and effective nuclear charge. These properties include: Ionization energy
  • 1.7.A.2.ii Trends in atomic properties within the periodic table (periodicity) can be predicted by the position of the element on the periodic table and qualitatively understood using Coulomb’s law, the shell model, and the concepts of shielding and effective nuclear charge. These properties include: Atomic and ionic radii

Lessons & Activities

T01.05 Atomic Structure and Electron Configuration

Learning Goals

  • 1.5.A Represent the ground-state electron configuration of an atom or its ions using the Aufbau principle.
  • 1.5.A.2 Coulomb’s law is used to calculate the force between two charged particles. Fcoulombic∝q1q2r2F_{\text{coulombic}} \propto \frac{q_1 q_2}{r^2}
  • 1.5.A.3 In atoms and ions, the electrons can be thought of as being in ‘shells’ (energy levels) and ‘subshells’ (sublevels), as described by the ground-state electron configuration. Inner electrons are called core electrons, and outer electrons are called valence electrons. The electron configuration is explained by quantum mechanics, as delineated in the Aufbau principle and exemplified in the periodic table of the elements.
  • 1.5.A.4 The relative energy required to remove an electron from different subshells of an atom or ion or from the same subshell in different atoms or ions (ionization energy) can be estimated through a qualitative application of Coulomb’s law. This energy is related to the distance from the nucleus and the effective (shield) charge of the nucleus.

Lessons & Activities

T01.07 Periodic Trends

Learning Goals

  • 1.7.A Explain the relationship between trends in atomic properties of elements and electronic structure and periodicity.
  • 1.7.A.2.iii Trends in atomic properties within the periodic table (periodicity) can be predicted by the position of the element on the periodic table and qualitatively understood using Coulomb’s law, the shell model, and the concepts of shielding and effective nuclear charge. These properties include: Electron affinity
  • 1.7.A.2.iv Trends in atomic properties within the periodic table (periodicity) can be predicted by the position of the element on the periodic table and qualitatively understood using Coulomb’s law, the shell model, and the concepts of shielding and effective nuclear charge. These properties include: Electronegativity
  • 1.7.A.3 The periodicity (in 1.7.A.2) is useful to predict/estimate values of properties in the absence of data.

Lessons & Activities

T01.01 Moles and Molar Mass

Learning Goals

  • 1.1.A Calculate quantities of a substance or its relative number of particles using dimensional analysis and the mole concept.
  • 1.1.A.1 One cannot count particles directly while performing laboratory work. Thus, there must be a connection between the masses of substances reacting and the actual number of particles undergoing chemical changes.
  • 1.1.A.2 Avogadro’s number (NA=6.022×1023 mol−1N_A = 6.022 \times 10^{23} \text{ mol}^{-1}) provides the connection between the number of moles in a pure sample of a substance and the number of constituent particles (or formula units) of that substance.
  • 1.1.A.3 Expressing the mass of an individual atom or molecule in atomic mass units (amu) is useful because the average mass in amu of one particle (atom or molecule) or formula unit of a substance will always be numerically equal to the molar mass of that substance in grams. Thus, there is a quantitative connection between the mass of a substance and the number of particles that the substance contains. EQN: n=mMn = \frac{m}{M}

Lessons & Activities

T01.02 Mass Spectra of the Elements

Learning Goals

  • 1.2.A Explain the quantitative relationship between the mass spectrum of an element and the masses of the element’s isotopes.
  • 1.2.A.1 The mass spectrum of a sample containing a single element can be used to determine the identity of the isotopes of that element and the relative abundance of each isotope in nature.
  • 1.2.A.2 The average atomic mass of an element can be estimated from the weighted average of the isotopic masses using the mass of each isotope and its relative abundance.

Lessons & Activities

  • (Interactive Simulation) PhET – Build a Nucleus Again note the element is determined by the number of protons, but neutrons still contribute to the mass. Nuclei are most stable when the neutron to proton ratio is around 1:1 or 3:2, so if you have too many protons or neutrons the nucleus will become less stable and essentially try to find a lower energy state by releasing excess particles until returning to that ratio. The half-life meter at the top of the simulation describes how quickly that nucleus would decay in nature.
  • (Video) Jeremy Krug – 1.2 Isotopes, Atomic Mass, & Mass Spectra of Elements
  • (Interactive Simulation) PhET – Isotopes and Atomic Mass This interactive is conceptually similar to the last, but rather than showing the types of decay, it shows the relative abundance of the isotope you create.

T01.03 Elemental Composition of Pure Substances

Learning Goals

  • 1.3.A Explain the quantitative relationship between the elemental composition by mass and the empirical formula of a pure substance.
  • 1.3.A.1 Some pure substances are composed of individual molecules, while others consist of atoms or ions held together in fixed proportions as described by a formula unit.
  • 1.3.A.2 According to the law of definite proportions, the ratio of the masses of the constituent elements in any pure sample of that compound is always the same.
  • 1.3.A.3 The chemical formula that lists the lowest whole number ratio of atoms of the elements in a compound is the empirical formula.

Lessons & Activities

T01.04 Composition of Mixtures

Learning Goals

  • 1.4.A Explain the quantitative relationship between the elemental composition by mass and the composition of substances in a mixture.
  • 1.4.A.1 Pure substances contain atoms, molecules, or formula units of a single type. Mixtures contain atoms, molecules, or formula units of two or more types, whose relative proportions can vary.
  • 1.4.A.2 Elemental analysis can be used to determine the relative numbers of atoms in a substance and to determine its purity.

Lessons & Activities

T01.06 Photoelectron Spectroscopy

Learning Goals

  • 1.6.A Explain the relationship between the photoelectron spectrum of an atom or ion and: i. The ground-state electron configuration of the species. ii. The interactions between the electrons and the nucleus.
  • 1.6.A.1 The energies of the electrons in a given shell can be measured experimentally with photoelectron spectroscopy (PES). The position of each peak in the PES spectrum is related to the energy required to remove an electron from the corresponding subshell, and the relative height of each peak is (ideally) proportional to the number of electrons in that subshell.

Lessons & Activities

T01.08 Valence Electrons and Ionic Compounds

Learning Goals

  • 1.8.A Explain the relationship between trends in the reactivity of elements and periodicity.
  • 1.8.A.1 The likelihood that two elements will form a chemical bond is determined by the interactions between the valence electrons and nuclei of elements.
  • 1.8.A.2 Elements in the same column of the periodic table tend to form analogous compounds.
  • 1.8.A.3 Typical charges of atoms in ionic compounds are governed by the number of valence electrons and predicted by their location on the periodic table.

Lessons & Activities

Unit 2….