Inorganic Chemistry ACS Exam Study Guide 2026–2027 | ACS
Inorganic Chemistry Exam Prep, Practice Questions with Answers
and Rationales, Atomic Structure, Periodicity, Bonding, Molecular
Orbital Theory, Coordination Chemistry, Symmetry, Group Theory,
Organ
Exam: ACS Standardized Inorganic Chemistry Exam
Format: Multiple-choice and free-response questions
Time: 90 minutes (typical)
Coverage: Atomic Structure, Periodicity, Bonding, Molecular Orbital Theory,
Coordination Chemistry, Symmetry, Group Theory, Organometallic
Chemistry, and Solid-State Chemistry
The ACS Inorganic Chemistry Exam is designed to assess a student's
mastery of fundamental and advanced inorganic principles, typically taken
at the end of a senior-level inorganic chemistry course. The exam
emphasizes conceptual understanding, problem-solving, and the
application of theoretical models to explain structure, bonding, and
reactivity.
Exam Content Areas & Weighting
Content Area Key Topics
Atomic Structure & Periodicity Spectra and orbitals, ionization energy,
electron affinity, shielding, effective nuclear charge, periodic trends
Covalent Bonding & Molecular Geometry VSEPR, valence bond
theory, hybridization, σ/π/δ bonds, molecular orbital theory
(homonuclear/heteronuclear diatomics)
,Coordination Chemistry Ligands, coordination number,
stereochemistry, nomenclature, ligand field theory, Jahn-Teller effects,
magnetic properties, spectrochemical series, term symbols
Symmetry & Group Theory Symmetry elements, operations, point group
assignment, character tables, applications to bonding and spectroscopy
Organometallic Chemistry Metal carbonyls, hydrocarbon ligands, 18-
electron rule, reaction mechanisms (oxidative addition, reductive
elimination, insertion), catalysis
Solid-State & Main Group Close packing, band theory, conductivity,
semiconductors, defects, main group element chemistry
Section 1: Atomic Structure & Periodicity (Questions 1–15)
Question 1
What is the electron configuration of iron (Fe, Z = 26)?
A. [Ar] 3d⁶ 4s²
B. [Ar] 3d⁸
C. [Ar] 3d⁵ 4s²
D. [Kr] 3d⁶ 4s²
Answer: A. [Ar] 3d⁶ 4s²
Rationale: Iron has atomic number 26. After the argon core (18 electrons),
the remaining 8 electrons fill as 3d⁶ 4s², following the Aufbau principle and
Hund's rule.
Question 2
Which element has the highest electronegativity among Na, Mg, Al, Cl, and
Si?
A. Na
,B. Mg
C. Al
D. Cl
E. Si
Answer: D. Cl
Rationale: Electronegativity increases across a period and up a group.
Chlorine is furthest right among the given elements in Period 3, giving it the
highest electronegativity (3.16 on the Pauling scale).
Question 3
Which statement correctly describes the trend in first ionization energy
across Period 3 from Na to Ar?
A. It decreases monotonically
B. It increases monotonically
C. It generally increases, with exceptions at Al and S
D. It generally decreases, with exceptions at Si and Cl
Answer: C. It generally increases, with exceptions at Al and S
Rationale: First ionization energy generally increases across a period due
to increasing effective nuclear charge. Exceptions occur at Al (electron
removed from 3p after stable 3s²) and S (electron removed from a paired
3p orbital, experiencing repulsion).
Question 4
, What is the ground-state term symbol for a free d² transition metal ion in
the gaseous phase?
A. ³P
B. ³F
C. ¹G
D. ¹D
Answer: B. ³F
Rationale: For a d² configuration, the maximum total magnetic quantum
number ML is 2 + 1 = 3, corresponding to L = 3 (F term). The maximum
total spin S is 1/2 + 1/2 = 1, yielding a spin multiplicity of 3, resulting in the
triplet F (³F) ground state according to Hund's rules.
Question 5
Which quantum number determines the shape of an atomic orbital?
A. Principal quantum number (n)
B. Angular momentum quantum number (l)
C. Magnetic quantum number (mₗ)
D. Spin quantum number (mₛ)
Answer: B. Angular momentum quantum number (l)
Rationale: The angular momentum quantum number (l) determines the
shape of the orbital (s, p, d, f). The principal quantum number determines
the energy level and size, while the magnetic quantum number determines
orientation.
Inorganic Chemistry Exam Prep, Practice Questions with Answers
and Rationales, Atomic Structure, Periodicity, Bonding, Molecular
Orbital Theory, Coordination Chemistry, Symmetry, Group Theory,
Organ
Exam: ACS Standardized Inorganic Chemistry Exam
Format: Multiple-choice and free-response questions
Time: 90 minutes (typical)
Coverage: Atomic Structure, Periodicity, Bonding, Molecular Orbital Theory,
Coordination Chemistry, Symmetry, Group Theory, Organometallic
Chemistry, and Solid-State Chemistry
The ACS Inorganic Chemistry Exam is designed to assess a student's
mastery of fundamental and advanced inorganic principles, typically taken
at the end of a senior-level inorganic chemistry course. The exam
emphasizes conceptual understanding, problem-solving, and the
application of theoretical models to explain structure, bonding, and
reactivity.
Exam Content Areas & Weighting
Content Area Key Topics
Atomic Structure & Periodicity Spectra and orbitals, ionization energy,
electron affinity, shielding, effective nuclear charge, periodic trends
Covalent Bonding & Molecular Geometry VSEPR, valence bond
theory, hybridization, σ/π/δ bonds, molecular orbital theory
(homonuclear/heteronuclear diatomics)
,Coordination Chemistry Ligands, coordination number,
stereochemistry, nomenclature, ligand field theory, Jahn-Teller effects,
magnetic properties, spectrochemical series, term symbols
Symmetry & Group Theory Symmetry elements, operations, point group
assignment, character tables, applications to bonding and spectroscopy
Organometallic Chemistry Metal carbonyls, hydrocarbon ligands, 18-
electron rule, reaction mechanisms (oxidative addition, reductive
elimination, insertion), catalysis
Solid-State & Main Group Close packing, band theory, conductivity,
semiconductors, defects, main group element chemistry
Section 1: Atomic Structure & Periodicity (Questions 1–15)
Question 1
What is the electron configuration of iron (Fe, Z = 26)?
A. [Ar] 3d⁶ 4s²
B. [Ar] 3d⁸
C. [Ar] 3d⁵ 4s²
D. [Kr] 3d⁶ 4s²
Answer: A. [Ar] 3d⁶ 4s²
Rationale: Iron has atomic number 26. After the argon core (18 electrons),
the remaining 8 electrons fill as 3d⁶ 4s², following the Aufbau principle and
Hund's rule.
Question 2
Which element has the highest electronegativity among Na, Mg, Al, Cl, and
Si?
A. Na
,B. Mg
C. Al
D. Cl
E. Si
Answer: D. Cl
Rationale: Electronegativity increases across a period and up a group.
Chlorine is furthest right among the given elements in Period 3, giving it the
highest electronegativity (3.16 on the Pauling scale).
Question 3
Which statement correctly describes the trend in first ionization energy
across Period 3 from Na to Ar?
A. It decreases monotonically
B. It increases monotonically
C. It generally increases, with exceptions at Al and S
D. It generally decreases, with exceptions at Si and Cl
Answer: C. It generally increases, with exceptions at Al and S
Rationale: First ionization energy generally increases across a period due
to increasing effective nuclear charge. Exceptions occur at Al (electron
removed from 3p after stable 3s²) and S (electron removed from a paired
3p orbital, experiencing repulsion).
Question 4
, What is the ground-state term symbol for a free d² transition metal ion in
the gaseous phase?
A. ³P
B. ³F
C. ¹G
D. ¹D
Answer: B. ³F
Rationale: For a d² configuration, the maximum total magnetic quantum
number ML is 2 + 1 = 3, corresponding to L = 3 (F term). The maximum
total spin S is 1/2 + 1/2 = 1, yielding a spin multiplicity of 3, resulting in the
triplet F (³F) ground state according to Hund's rules.
Question 5
Which quantum number determines the shape of an atomic orbital?
A. Principal quantum number (n)
B. Angular momentum quantum number (l)
C. Magnetic quantum number (mₗ)
D. Spin quantum number (mₛ)
Answer: B. Angular momentum quantum number (l)
Rationale: The angular momentum quantum number (l) determines the
shape of the orbital (s, p, d, f). The principal quantum number determines
the energy level and size, while the magnetic quantum number determines
orientation.
