,CHEM 121 Module Exam 3 Portage General
Chemistry w/Lab 100% Correct
Bonding
1. Which statement best describes an ionic bond?
A) It is the attraction between temporary dipoles only.
B) It is the equal sharing of electrons between identical atoms.
C) It is the electrostatic attraction between oppositely charged ions.
D) It is the overlap of two filled atomic orbitals without electron transfer.
Correct Answer: C) It is the electrostatic attraction between oppositely charged ions.
Rationale: Ionic bonding results when atoms form cations and anions and those opposite charges attract.
Electron transfer commonly produces the ions, but the bond itself is the electrostatic attraction between them.
Equal sharing describes nonpolar covalent bonding, while temporary dipoles are intermolecular rather than ionic
bonds.
2. Which pair is most likely to form an ionic compound?
A) Cl and Br
B) Na and Cl
C) N and H
D) C and O
Correct Answer: B) Na and Cl
Rationale: A metal such as sodium readily loses an electron, while a nonmetal such as chlorine readily gains
one, producing Na+ and Cl-. The other pairs are composed of nonmetals and therefore more commonly form
covalent bonds.
3. When a magnesium atom forms Mg2+, what has occurred?
A) The nucleus has lost two protons.
B) The atom has gained two electrons.
C) The atom has lost two electrons.
D) Two neutrons have been removed.
Correct Answer: C) The atom has lost two electrons.
Rationale: A positive ion forms when electrons are lost. Magnesium commonly loses its two valence electrons to
achieve a stable noble-gas-like configuration, giving Mg2+. Changing proton number would change the element
itself.
4. Which compound is expected to contain primarily covalent bonds?
A) CO2
B) MgO
C) CaF2
D) NaCl
Correct Answer: A) CO2
Rationale: Carbon and oxygen are both nonmetals, so they bond by sharing electrons. Sodium chloride,
magnesium oxide, and calcium fluoride combine metals with nonmetals and are primarily ionic.
CHEM 121 Module 3 - Original Practice Study Guide Page 2
, 5. Why do atoms form chemical bonds?
A) Bonding can lower the potential energy of the system and produce more stable electron arrangements.
B) Bonding converts every atom into a noble gas atom.
C) Bonding eliminates all electrostatic forces.
D) Bonding always increases the number of protons.
Correct Answer: A) Bonding can lower the potential energy of the system and produce more stable
electron
arrangements.
Rationale: Chemical bonding is favored when the bonded arrangement is energetically more stable than
separated atoms. Atoms often achieve favorable valence-shell configurations, but they do not literally become
noble-gas atoms, and electrostatic forces remain fundamental to bonding.
6. Which description best fits a nonpolar covalent bond?
A) One atom completely transfers an electron to the other.
B) The bonding electrons are shared approximately equally between the two atoms.
C) Only ions are present.
D) Electrons are shared very unequally because of a large electronegativity difference.
Correct Answer: B) The bonding electrons are shared approximately equally between the two atoms.
Rationale: When bonded atoms have identical or very similar electronegativities, the shared electron density is
distributed relatively evenly. Complete transfer is associated with ionic bonding; unequal sharing produces a
polar covalent bond.
7. In a polar covalent bond, the more electronegative atom generally has what kind of charge?
A) A full positive charge
B) A partial positive charge
C) No electron density around it
D) A partial negative charge
Correct Answer: D) A partial negative charge
Rationale: The more electronegative atom attracts the shared electrons more strongly, giving it greater electron
density and a partial negative charge. The less electronegative partner becomes partially positive.
8. Which trend generally increases bond polarity?
A) A smaller electronegativity difference
B) A larger electronegativity difference between the bonded atoms
C) A lower number of neutrons only
D) Identical electronegativities
Correct Answer: B) A larger electronegativity difference between the bonded atoms
Rationale: Bond polarity arises from unequal sharing of bonding electrons. A larger electronegativity difference
produces a larger separation of partial charge and therefore a more polar bond.
9. Which statement about lattice energy is generally correct?
A) It is unrelated to ion charge.
B) It tends to increase in magnitude as ionic charges increase and ionic sizes decrease.
C) It decreases in magnitude when ions are smaller and more highly charged.
D) It applies only to molecular covalent substances.
Correct Answer: B) It tends to increase in magnitude as ionic charges increase and ionic sizes decrease.
CHEM 121 Module 3 - Original Practice Study Guide Page 3
Chemistry w/Lab 100% Correct
Bonding
1. Which statement best describes an ionic bond?
A) It is the attraction between temporary dipoles only.
B) It is the equal sharing of electrons between identical atoms.
C) It is the electrostatic attraction between oppositely charged ions.
D) It is the overlap of two filled atomic orbitals without electron transfer.
Correct Answer: C) It is the electrostatic attraction between oppositely charged ions.
Rationale: Ionic bonding results when atoms form cations and anions and those opposite charges attract.
Electron transfer commonly produces the ions, but the bond itself is the electrostatic attraction between them.
Equal sharing describes nonpolar covalent bonding, while temporary dipoles are intermolecular rather than ionic
bonds.
2. Which pair is most likely to form an ionic compound?
A) Cl and Br
B) Na and Cl
C) N and H
D) C and O
Correct Answer: B) Na and Cl
Rationale: A metal such as sodium readily loses an electron, while a nonmetal such as chlorine readily gains
one, producing Na+ and Cl-. The other pairs are composed of nonmetals and therefore more commonly form
covalent bonds.
3. When a magnesium atom forms Mg2+, what has occurred?
A) The nucleus has lost two protons.
B) The atom has gained two electrons.
C) The atom has lost two electrons.
D) Two neutrons have been removed.
Correct Answer: C) The atom has lost two electrons.
Rationale: A positive ion forms when electrons are lost. Magnesium commonly loses its two valence electrons to
achieve a stable noble-gas-like configuration, giving Mg2+. Changing proton number would change the element
itself.
4. Which compound is expected to contain primarily covalent bonds?
A) CO2
B) MgO
C) CaF2
D) NaCl
Correct Answer: A) CO2
Rationale: Carbon and oxygen are both nonmetals, so they bond by sharing electrons. Sodium chloride,
magnesium oxide, and calcium fluoride combine metals with nonmetals and are primarily ionic.
CHEM 121 Module 3 - Original Practice Study Guide Page 2
, 5. Why do atoms form chemical bonds?
A) Bonding can lower the potential energy of the system and produce more stable electron arrangements.
B) Bonding converts every atom into a noble gas atom.
C) Bonding eliminates all electrostatic forces.
D) Bonding always increases the number of protons.
Correct Answer: A) Bonding can lower the potential energy of the system and produce more stable
electron
arrangements.
Rationale: Chemical bonding is favored when the bonded arrangement is energetically more stable than
separated atoms. Atoms often achieve favorable valence-shell configurations, but they do not literally become
noble-gas atoms, and electrostatic forces remain fundamental to bonding.
6. Which description best fits a nonpolar covalent bond?
A) One atom completely transfers an electron to the other.
B) The bonding electrons are shared approximately equally between the two atoms.
C) Only ions are present.
D) Electrons are shared very unequally because of a large electronegativity difference.
Correct Answer: B) The bonding electrons are shared approximately equally between the two atoms.
Rationale: When bonded atoms have identical or very similar electronegativities, the shared electron density is
distributed relatively evenly. Complete transfer is associated with ionic bonding; unequal sharing produces a
polar covalent bond.
7. In a polar covalent bond, the more electronegative atom generally has what kind of charge?
A) A full positive charge
B) A partial positive charge
C) No electron density around it
D) A partial negative charge
Correct Answer: D) A partial negative charge
Rationale: The more electronegative atom attracts the shared electrons more strongly, giving it greater electron
density and a partial negative charge. The less electronegative partner becomes partially positive.
8. Which trend generally increases bond polarity?
A) A smaller electronegativity difference
B) A larger electronegativity difference between the bonded atoms
C) A lower number of neutrons only
D) Identical electronegativities
Correct Answer: B) A larger electronegativity difference between the bonded atoms
Rationale: Bond polarity arises from unequal sharing of bonding electrons. A larger electronegativity difference
produces a larger separation of partial charge and therefore a more polar bond.
9. Which statement about lattice energy is generally correct?
A) It is unrelated to ion charge.
B) It tends to increase in magnitude as ionic charges increase and ionic sizes decrease.
C) It decreases in magnitude when ions are smaller and more highly charged.
D) It applies only to molecular covalent substances.
Correct Answer: B) It tends to increase in magnitude as ionic charges increase and ionic sizes decrease.
CHEM 121 Module 3 - Original Practice Study Guide Page 3
