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Required Course Content:
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
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.
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.
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.
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.
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.
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.
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. 
TOPIC 2.1
Types of
Chemical Bonds
Required Course Content
ENDURING UNDERSTANDING
SAP-3
Atoms or ions bond due to interactions between them, forming molecules.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SAP-3.A
Explain the relationship
between the type of bonding
and the properties of the
elements participating in
the bond.
SAP-3.A.1
Electronegativity values for the representative
elements increase going from left to right
across a period and decrease going down
a group. These trends can be understood
qualitatively through the electronic structure of
the atoms, the shell model, and Coulomb’s law.
SAP-3.A.2
Valence electrons shared between atoms
of similar electronegativity constitute a
nonpolar covalent bond. For example, bonds
between carbon and hydrogen are effectively
nonpolar even though carbon is slightly more
electronegative than hydrogen.
SAP-3.A.3
Valence electrons shared between atoms of
unequal electronegativity constitute a polar
covalent bond.
a. The atom with a higher electronegativity will
develop a partial negative charge relative to
the other atom in the bond.
b. In single bonds, greater differences in
electronegativity lead to greater bond dipoles.
c. All polar bonds have some ionic character,
and the difference between ionic and
covalent bonding is not distinct but rather
a continuum.SAP-3.A.4
The difference in electronegativity is not the
only factor in determining if a bond should
be designated as ionic or covalent. Generally,
bonds between a metal and nonmetal are
ionic, and bonds between two nonmetals are
covalent. Examination of the properties of a
compound is the best way to characterize the
type of bonding.
SAP-3.A.5
In a metallic solid, the valence electrons
from the metal atoms are considered to be
delocalized and not associated with any
individual atom.
TOPIC 2.2
Intramolecular Force
and Potential Energy
Required Course Content
ENDURING UNDERSTANDING
SAP-3
Atoms or ions bond due to interactions between them, forming molecules.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SAP-3.B
Represent the relationship
between potential energy
and distance between
atoms, based on factors that
influence the interaction
strength.
SAP-3.B.1
A graph of potential energy versus the distance
between atoms is a useful representation for
describing the interactions between atoms.
Such graphs illustrate both the equilibrium
bond length (the separation between atoms at
which the potential energy is lowest) and the
bond energy (the energy required to separate
the atoms).
SAP-3.B.2
In a covalent bond, the bond length is
influenced by both the size of the atom’s core
and the bond order (i.e., single, double, triple).
Bonds with a higher order are shorter and have
larger bond energies.
SAP-3.B.3
Coulomb’s law can be used to understand the
strength of interactions between cations
and anions.
a. Because the interaction strength is
proportional to the charge on each ion, larger
charges lead to stronger interactions.
b. Because the interaction strength increases
as the distance between the centers of the
ions (nuclei) decreases, smaller ions lead to
stronger interactions.
TOPIC 2.3
Structure of
Ionic Solids
Required Course Content
ENDURING UNDERSTANDING
SAP-3
Atoms or ions bond due to interactions between them, forming molecules.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SAP-3.C
Represent an ionic solid with
a particulate model that is
consistent with Coulomb’s
law and the properties of the
constituent ions.
SAP-3.C.1
The cations and anions in an ionic crystal are
arranged in a systematic, periodic 3-D array
that maximizes the attractive forces among
cations and anions while minimizing the
repulsive forces.
X KNOWLEDGE OF SPECIFIC TYPES OF
CRYSTAL STRUCTURES WILL NOT BE
ASSESSED ON THE AP EXAM.
Rationale: Study of specific crystal structures is
not essential to an understanding of the big ideas.
TOPIC 2.4
Structure of Metals
and Alloys
Required Course Content
ENDURING UNDERSTANDING
SAP-3
Atoms or ions bond due to interactions between them, forming molecules.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SAP-3.D
Represent a metallic
solid and/or alloy using a
model to show essential
characteristics of the
structure and interactions
present in the substance.
SAP-3.D.1
Metallic bonding can be represented as an
array of positive metal ions surrounded by
delocalized valence electrons (i.e., a “sea
of electrons”).
SAP-3.D.2
Interstitial alloys form between atoms of
different radii, where the smaller atoms fill the
interstitial spaces between the larger atoms
(e.g., with steel in which carbon occupies the
interstices in iron).
SAP-3.D.3
Substitutional alloys form between atoms
of comparable radius, where one atom
substitutes for the other in the lattice. (In
certain brass alloys, other elements, usually
zinc, substitute for copper.)
TOPIC 2.5
Lewis Diagrams
Required Course Content
ENDURING UNDERSTANDING
SAP-4
Molecular compounds are arranged based on Lewis diagrams and Valence Shell
Electron Pair Repulsion (VSEPR) theory.
LEARNING OBJECTIVE
SAP-4.A
Represent a molecule with a
Lewis diagram.
ESSENTIAL KNOWLEDGE
SAP-4.A.1
Lewis diagrams can be constructed according
to an established set of principles.
TOPIC 2.6
Resonance and
Formal Charge
Required Course Content
ENDURING UNDERSTANDING
SAP-4
Molecular compounds are arranged based on Lewis diagrams and Valence Shell
Electron Pair Repulsion (VSEPR) theory.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SAP-4.B
Represent a molecule with a
Lewis diagram that accounts
for resonance between
equivalent structures or that
uses formal charge to select
between nonequivalent
structures.
SAP-4.B.1
In cases where more than one equivalent Lewis
structure can be constructed, resonance
must be included as a refinement to the Lewis
structure. In many such cases, this refinement
is needed to provide qualitatively accurate
predictions of molecular structure
and properties.
SAP-4.B.2
The octet rule and formal charge can be used
as criteria for determining which of several
possible valid Lewis diagrams provides the
best model for predicting molecular structure
and properties.
SAP-4.B.3
As with any model, there are limitations to
the use of the Lewis structure model,
particularly in cases with an odd number of
valence electrons. 
TOPIC 2.7
VSEPR and Bond
Hybridization
Required Course Content
ENDURING UNDERSTANDING
SAP-4
Molecular compounds are arranged based on Lewis diagrams and Valence Shell
Electron Pair Repulsion (VSEPR) theory.
LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE
SAP-4.C
Based on the relationship
between Lewis diagrams,
VSEPR theory, bond orders,
and bond polarities:
a. Explain structural
properties of molecules.
b. Explain electron properties
of molecules.
SAP-4.C.1
VSEPR theory uses the Coulombic repulsion
between electrons as a basis for predicting
the arrangement of electron pairs around a
central atom.
SAP-4.C.2
Both Lewis diagrams and VSEPR theory must
be used for predicting electronic and structural
properties of many covalently bonded
molecules and polyatomic ions, including
the following:
a. Molecular geometry
b. Bond angles
c. Relative bond energies based on bond order
d. Relative bond lengths (multiple bonds,
effects of atomic radius)
e. Presence of a dipole moment
f. Hybridization of valence orbitals of
the molecule
SAP-4.C.3
The terms “hybridization” and “hybrid atomic
orbital” are used to describe the arrangement
of electrons around a central atom. When the
central atom is sp hybridized, its ideal bond
angles are 180°; for sp2 hybridized atoms the
bond angles are 120°; and for sp3 hybridized
atoms the bond angles are 109.5°.
X AN UNDERSTANDING OF THE DERIVATION
AND DEPICTION OF HYBRID ORBITALS
WILL NOT BE ASSESSED ON THE AP EXAM.
Rationale: The course includes the distinction
between sigma and pi bonding, the use of VSEPR
to explain the shapes of molecules, and the sp,
sp2
, and sp3
 nomenclature. Additional aspects
related to hybridization are both controversial and
do not substantially enhance understanding of
molecular structure.
X HYBRIDIZATION INVOLVING D ORBITALS
WILL NOT BE ASSESSED ON THE AP EXAM.
WHEN AN ATOM HAS MORE THAN FOUR
PAIRS OF ELECTRONS SURROUNDING THE
CENTRAL ATOM, STUDENTS ARE ONLY
RESPONSIBLE FOR THE SHAPE OF THE
RESULTING MOLECULE.
Rationale: Current evidence suggests that
main-group hybridization involving d orbitals
does not exist, and there is controversy about the
need to teach any hybridization. Until agreement
is reached in the chemistry community, we
will continue to include only sp, sp2
, and sp3
hybridization on the AP Exam.
SAP-4.C.4
Bond formation is associated with overlap
between atomic orbitals. In multiple bonds, such
overlap leads to the formation of both sigma
and pi bonds. The overlap is stronger in sigma
than pi bonds, which is reflected in sigma bonds
having greater bond energy than pi bonds. The
presence of a pi bond also prevents the rotation
of the bond and leads to structural isomers.
X MOLECULAR ORBITAL THEORY IS
RECOMMENDED AS A WAY TO PROVIDE
DEEPER INSIGHT INTO BONDING.
HOWEVER, THE AP EXAM WILL NEITHER
EXPLICITLY ASSESS MOLECULAR ORBITAL
DIAGRAMS, FILLING OF MOLECULAR
ORBITALS, NOR THE DISTINCTION
BETWEEN BONDING, NONBONDING, AND
ANTIBONDING ORBITALS.
Rationale: As currently covered in general
chemistry college textbooks, molecular orbital
theory is limited to homonuclear molecules in the
second period.