Here is some required course content. What would you teach? Use the article to guide you: he danger of failing to interpret and contextualize the CED

September 19, 2023
The AP Chemistry Course & Exam Description (CED) is the document that tells teachers the content can be examined on the AP Chemistry exam in May of each year. As an AP Chemistry teacher, the CED is the single most important guide to the teaching of the course, so when questions arise about what content is in – and just as importantly what content is out – is it just as simple as searching the CED to find the relevant phrase? Unfortunately, the answer is no.

I often see AP Chemistry teachers ask questions such as, “Should I teach combustion analysis” followed by, “I searched the CED and couldn’t find it”. Well, be careful! There’s a real danger in searching that document and drawing the conclusion that if a particular phrase is not present then that means a topic is not examinable. The simple explanation of the disconnect lies in interpretation and context.

Let’s take combustion analysis as an example. The better question to ask about teaching it is, “Would teaching combustion analysis involve the calculation of moles, the application of stoichiometry, and the possible calculation of empirical and/or molecular formula?” Well, I think we all know the answer to those questions, and hence combustion analysis’s potential relevance to an AP chemistry course.

A similar (but different) example is the question of teaching paramagentism and diamagnetism. I have dealt with that question here. In this instance the conversation revolves around the way that LOs connected with electronic configuration might be interpreted beyond the literal. I have a simple test for this. I ask myself, “If a question about [blank] came up on the exam, would I feel it “unfair”?”  With paramagnetism I would not, so it’s “in” for me. It should be noted that teaching something like paramagnetism is such a low impact topic in terms of time and deviation from what I have to teach about electronic configuration anyway, that it’s almost a nothing-burger, and perhaps time might make a difference in other examples.

Finally I deal with balancing REDOX in acid and base here. This treatment is similar to that related to paramagnetism in as much as it involves an interpretation of LOs rather than their literal reading, but also goes further. I feel there is just too much value in teaching balancing REDOX in acid and base for other areas of the course for it to be ignored.

It’s still true that the literal reading of the CED is vital, but so are these other ways to consume it. In the first instance combustion is essentially just another name for a bunch of things that are explicitly listed in the CED; the second example is a “safety first” approach, where a wider interpretation of the application of LOs means that I teach something that I feel feasibly could be examined; and thirdly there’s an example of a topic that I don’t think will be examined literally, but offers way too much value across other areas of the examinable curriculum for it to be omitted. Each of these is subtlety different, but each offers a window into the CED that goes beyond just “Ctrl+F”.

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.