Tell me what I need to teach. UNIT OPENERS
Developing Understanding provides an overview that
contextualizes and situates the key content of the unit within
the scope of the course.
Big ideas serve as the foundation of the course and help
develop understanding as they spiral throughout the course.
The essential questions are thought-provoking questions that
motivate students and inspire inquiry.
Building the Science Practices describes specific aspects of
the practices that are appropriate to focus on in that unit.
Preparing for the AP Exam provides helpful tips and common
student misunderstandings identified from prior exam data. The Unit at a Glance table shows the topics, related enduring
understandings, and suggested skills. The class periods
column has been left blank so that teachers can customize the
time they spend on each topic.
The suggested skill for each topic shows one way to link
the content in that topic to a specific AP Chemistry skill. The
individual skills have been thoughtfully chosen in a way that
allows teachers to scaffold the practices throughout the
course. The questions on the Personal Progress Checks are
based on this pairing. However, AP Exam questions can pair the
content with any of the skills. The Sample Instructional Activities page includes optional
activities that can help tie together the content and skill of a
particular topic. Enduring understandings are the long-term takeaways related
to the big ideas that leave a lasting impression on students.
The suggested skill offers a possible skill to pair with the topic.
Where possible, available resources are provided that might
help teachers address a particular topic.
Learning objectives define what a student needs to be able
to do with content knowledge in order to progress toward the
enduring understandings.
Essential knowledge statements describe the knowledge
required to perform the learning objective.
Exclusion statements define content or specific details about
content that will not be assessed on the AP Chemistry Exam.
However, such content may be provided as background or
additional information for the concepts and science practices
being assessed.
UNIT
1
Developing Understanding
This first unit sets the foundation for the course by examining the atomic theory of matter,
the fundamental premise of chemistry. Although atoms represent the foundational level
of chemistry, observations of chemical properties are made on collections of atoms.
Macroscopic systems involve such large numbers that they require moles as a unit of
comparison. The periodic table provides information about each element’s predictable
periodicity as a function of the atomic number. The electronic structure of an atom can
be described by an electron configuration that provides a method for describing the
distribution of electrons in an atom or ion. In subsequent units, students will apply their
understanding of atomic structure to models and representations of chemical phenomena
and explain changes and interactions of chemical substances.
Building the
Science Practices
1.A 2.A 4.A 4.B 4.C 5.A 5.B 5.D
In Unit 1, students will practice identifying
components of commonly used models
and representations to illustrate chemical
phenomena. They will construct models
and representations and explain whether
they are consistent with chemical theories.
Students will also practice translating
between data and various representations
(e.g., photoelectron spectroscopy data
and electron configurations). Students
should then be able to use representations
(e.g., PES graphs, electron configurations,
periodic table, drawings) to explain atomic
structure, which is the foundation for all
subsequent units.
Many of the most useful concepts in
chemistry relate to patterns in the behavior
of chemical systems, such as periodic trends
in atomic and molecular properties. In this
unit and all subsequent units, students
should learn to analyze data presented
graphically to identify patterns and
relationships. Once a pattern is identified,
students should be able to examine evidence
to determine if it supports the pattern or
hypothesis pertaining to a testable question.
Preparing for the AP Exam
On the AP Exam, students must be able
to justify claims with evidence. This starts
when students can identify the evidence
needed to solve a problem or support a claim
and then connect that evidence to known
chemical theories. However, many students
consistently demonstrate difficulty with
this skill. For example, while students can
memorize periodic trends, they struggle to
explain the electrostatic interactions within
an atom that produces period trends as
well as exceptions to these trends. Further,
students often have difficulty connecting
periodic trends to the shell model, Coulomb’s
law, and elements of quantum theory.
To combat these challenges, teachers
can ensure that students have a strong
foundation in identifying mathematical
relationships or patterns from graphical or
tabular information and that they can explain
how those patterns are consistent with
chemical theories and models.
UNIT AT A GLANCE ingEndur Understanding
Topic Suggested Skill
Class Periods
~9–10 CLASS PERIODS
-1PQS
1.1 Moles and Molar Mass 5.B  Identify an appropriate theory, definition, or
mathematical relationship to solve a problem.
1.2 Mass Spectroscopy of
Elements
5.D  Identify information presented graphically to
solve a problem.
-2PQS
1.3 Elemental Composition of
Pure Substances
2.A  Identify a testable scientific question based on
an observation, data, or a model.
1.4 Composition of Mixtures 5.A  Identify quantities needed to solve a problem
from given information (e.g., text, mathematical
expressions, graphs, or tables).
-1APS
1.5 Atomic Structure and
Electron Configuration
1.A  Describe the components of and quantitative
information from models and representations that
illustrate particulate-level properties only.
1.6 Photoelectron
Spectroscopy
4.B  Explain whether a model is consistent with
chemical theories.
-2APS
1.7 Periodic Trends 4.A  Explain chemical properties or phenomena
(e.g., of atoms or molecules) using given chemical
theories, models, and representations.
1.8 Valence Electrons and
Ionic Compounds
4.C  Explain the connection between particulatelevel and macroscopic properties of a substance
using models and representations. 
UNIT
1
TOPIC 1.1
Moles and
Molar Mass
Required Course Content
ENDURING UNDERSTANDING
SPQ-1
The mole allows different units to be compared.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SPQ-1.A
Calculate quantities of a
substance or its relative
number of particles using
dimensional analysis and the
mole concept.
SPQ-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.
SPQ-1.A.2
Avogadro’s number (N = 6.022 × 1023 mol−1
A )
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.
SPQ-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 = m/M
SUGGESTED SKILL
Mathematical
Routines
5.B
Identify an appropriate
theory, definition, or
mathematical relationship
to solve a problem.
AVAILABLE RESOURCES
§ Classroom Resource >
Quantitative Skills in
the AP Sciences
§ AP Chemistry Lab
Manual > Investigation
3: What Makes Hard
Water Hard?
§ Classroom Resource >
Guided Inquiry
Activities for the
Classroom: Lesson 1
Atomic Structure and Properties
UNIT
1
TOPIC 1.2
Mass Spectroscopy
of Elements
Required Course Content
ENDURING UNDERSTANDING
SPQ-1
The mole allows different units to be compared.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SPQ-1.B
Explain the quantitative
relationship between the
mass spectrum of an element
and the masses of the
element’s isotopes.
SPQ-1.B.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.
SPQ-1.B.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.
X INTERPRETING MASS SPECTRA
Interpreting mass spectra of samples
containing multiple elements or peaks arising
from species other than singly charged
monatomic ions will not be assessed on
the AP Exam.
SUGGESTED SKILL
Mathematical
Routines
5.D
Identify information
presented graphically to
solve a problem.
AVAILABLE RESOURCES
§ Classroom Resource >
Course Framework V.1 |
Return to Table of Cont
© 2022 College Boar
ents
d
Exploring Atomic
Structure Using
Photoelectron
Spectroscopy (PES)
Data
UNIT
1
TOPIC 1.3
Elemental
Composition of
Pure Substances
Required Course Content
ENDURING UNDERSTANDING
SPQ-2
Chemical formulas identify substances by their unique combination of atoms.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SPQ-2.A
Explain the quantitative
relationship between the
elemental composition by
mass and the empirical
formula of a pure substance.
SPQ-2.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.
SPQ-2.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.
SPQ-2.A.3
The chemical formula that lists the lowest
whole number ratio of atoms of the elements in
a compound is the empirical formula.
SUGGESTED SKILL
Question and
Method
2.A
Identify a testable scientific
question based on an
observation, data, or
a model.
AVAILABLE RESOURCES
§ AP Chemistry
Lab Manual >
Investigation 3: What
Makes Hard Water
Hard?
Atomic Structure and Properties
UNIT
1
TOPIC 1.4
Composition
of Mixtures
Required Course Content
ENDURING UNDERSTANDING
SPQ-2
Chemical formulas identify substances by their unique combination of atoms.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SPQ-2.B
Explain the quantitative
relationship between the
elemental composition by
mass and the composition of
substances in a mixture.
SPQ-2.B.1
While pure substances contain molecules or
formula units of a single type, mixtures contain
molecules or formula units of two or more
types, whose relative proportions can vary.
SPQ-2.B.2
Elemental analysis can be used to determine
the relative numbers of atoms in a substance
and to determine its purity.
SUGGESTED SKILL
Mathematical
Routines
5.A
Identify quantities needed
to solve a problem from
given information (e.g., text,
mathematical expressions,
graphs, or tables).
AVAILABLE RESOURCES
§ Classroom Resource >
Quantitative Skills in the
AP Sciences
TOPIC 1.5
Atomic Structure and
Electron Configuration
Required Course Content
ENDURING UNDERSTANDING
SAP-1
Atoms and molecules can be identified by their electron distribution and energy.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SAP-1.A
Represent the electron
configuration of an element
or ions of an element using
the Aufbau principle.
SAP-1.A.1
The atom is composed of negatively charged
electrons and a positively charged nucleus that
is made of protons and neutrons.
SAP-1.A.2
Coulomb’s law is used to calculate the force
between two charged particles.
EQN: Fcoulombic ∝ q1
q2
r2
SAP-1.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
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.
X THE ASSIGNMENT OF QUANTUM NUMBERS
TO ELECTRONS IN SUBSHELLS OF AN
ATOM WILL NOT BE ASSESSED ON THE
AP EXAM.
Rationale: Assignment of quantum numbers
to electrons in specific subshells does not
increase students’ understanding of the
structure of the atom.
SUGGESTED SKILL
Models and
Representations
1.A
Describe the components
of and quantitative
information from models
and representations that
illustrate particulate-level
properties only.
AVAILABLE RESOURCES
§ Classroom Resource >
Alternative Approaches
to Teaching Traditional
Topics
continued on next page
SAP-1.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. 
TOPIC 1.6
Photoelectron
Spectroscopy
ENDURING UNDERSTANDING
SAP-1
Atoms and molecules can be identified by their electron distribution and energy.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SAP-1.B
Explain the relationship
between the photoelectron
spectrum of an atom or
ion and:
a. The electron configuration
of the species.
b. The interactions
between the electrons
and the nucleus.
SAP-1.B.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 height of each peak is (ideally) proportional
to the number of electrons in that subshell.
SUGGESTED SKILL
Model Analysis
4.B
Explain whether a model is
consistent with chemical
theories.
AVAILABLE RESOURCES
§ Classroom Resource >
Exploring Atomic
Structure Using
Photoelectron
Spectroscopy
(PES) Data
TOPIC 1.7
Periodic Trends
Required Course Content
ENDURING UNDERSTANDING
SAP-2
The periodic table shows patterns in electronic structure and trends in
atomic properties.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SAP-2.A
Explain the relationship
between trends in atomic
properties of elements and
electronic structure
and periodicity.
SAP-2.A.1
The organization of the periodic table is based
on the recurring properties of the elements and
explained by the pattern of electron configurations
and the presence of completely or partially filled
shells (and subshells) of electrons in atoms.
X WRITING THE ELECTRON CONFIGURATION
OF ELEMENTS THAT ARE EXCEPTIONS
TO THE AUFBAU PRINCIPLE WILL NOT BE
ASSESSED ON THE AP EXAM.
Rationale: The mere rote recall of the
exceptions does not match the goals of the
curriculum revision.
SAP-2.A.2
Trends in atomic properties within the
periodic table (periodicity) can be qualitatively
understood through the position of the element
in the periodic table, Coulomb’s law, the shell
model, and the concept of shielding/effective
nuclear charge. These properties include:
a. Ionization energy
b. Atomic and ionic radii
c. Electron affinity
d. Electronegativity.
SAP-2.A.3
The periodicity (in SAP-2.A.2) is useful to
predict /estimate values of properties in the
absence of data.
SUGGESTED SKILL
Model Analysis
4.A
Explain chemical properties
or phenomena (e.g., of
atoms or molecules)
using given chemical
theories, models, and
representations.
AVAILABLE RESOURCES
§ Classroom Resource >
Alternative Approaches
to Teaching Traditional
Topics
TOPIC 1.8
Valence Electrons and
Ionic Compounds
Required Course Content
ENDURING UNDERSTANDING
SAP-2
The periodic table shows patterns in electronic structure and trends in
atomic properties.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SAP-2.B
Explain the relationship
between trends in the
reactivity of elements
and periodicity.
SAP-2.B.1
The likelihood that two elements will form
a chemical bond is determined by the
interactions between the valence electrons
and nuclei of elements.
SAP-2.B.2
Elements in the same column of the periodic
table tend to form analogous compounds.
SAP-2.B.3
Typical charges of atoms in ionic compounds
are governed by their location on the periodic
table and the number of valence electrons.
SUGGESTED SKILL
Model Analysis
4.C
Explain the connection
between particulatelevel and macroscopic
properties of a substance
using models and
representations.
AVAILABLE RESOURCES
§ Classroom Resource >
Alternative Approaches
to Teaching Traditional
Topics