CHEM 121 Foundations of General Chemistry: Ionic & Covalent Bonds,
Naming, and Lewis Structures 2026/2027 UPDATE
1. Which type of chemical bond involves the transfer of electrons from one
atom to another?
A. Covalent bond
B. Metallic bond
C. Ionic bond
D. Hydrogen bond
Answer: C
Rationale: Ionic bonds are formed when one atom transfers electrons to another, typically
between a metal and a non-metal.
2. In the Lewis structure for H2O, how many lone pairs of electrons are on the
central oxygen atom?
A. 1
B. 3
C. 2
D. 0
Answer: C
Rationale: Oxygen has 6 valence electrons; 2 are used for bonding with Hydrogen, leaving
4 electrons or 2 lone pairs.
,3. What is the correct name for the compound FeCl3?
A. Iron trichloride
B. Iron(II) chloride
C. Ferrous chloride
D. Iron(III) chloride
Answer: D
Rationale: Iron is a transition metal with variable charges. Since Chlorine has a -1 charge,
Iron must be +3 to balance the three chlorides.
4. What is the name of the molecular compound N2O4?
A. Nitrogen oxide
B. Nitrogen tetroxide
C. Dinitrogen tetroxide
D. Dinitrogen quadroxide
Answer: C
Rationale: For molecular compounds, Greek prefixes are used: ‘di-’ for two and ‘tetra-’ for
four.
5. Which of the following elements is an exception to the octet rule and can
have an expanded octet?
A. Carbon
B. Phosphorus
C. Oxygen
D. Nitrogen
Answer: B
Rationale: Elements in the third period and below, such as Phosphorus, have d-orbitals
that allow them to hold more than 8 electrons.
, 6. What is the correct formula for Magnesium phosphate?
A. MgPO4
B. Mg2PO4
C. Mg3PO4
D. Mg3(PO4)2
Answer: D
Rationale: Magnesium has a +2 charge and phosphate (PO4) has a -3 charge; to balance,
we need three Mg and two PO4.
7. A covalent bond where electrons are shared unequally is called:
A. Nonpolar covalent
B. Coordinate covalent
C. Ionic
D. Polar covalent
Answer: D
Rationale: A polar covalent bond occurs when there is a difference in electronegativity
between the two atoms, causing unequal sharing.
8. What is the formal charge of the Nitrogen atom in the ammonium ion
(NH4+)?
A. 0
B. -1
C. +1
D. +2
Answer: C
Rationale: Formal charge = Valence electrons - (lone pair electrons + 1/2 bonding
electrons). For N: 5 - (0 + 4) = +1.
Naming, and Lewis Structures 2026/2027 UPDATE
1. Which type of chemical bond involves the transfer of electrons from one
atom to another?
A. Covalent bond
B. Metallic bond
C. Ionic bond
D. Hydrogen bond
Answer: C
Rationale: Ionic bonds are formed when one atom transfers electrons to another, typically
between a metal and a non-metal.
2. In the Lewis structure for H2O, how many lone pairs of electrons are on the
central oxygen atom?
A. 1
B. 3
C. 2
D. 0
Answer: C
Rationale: Oxygen has 6 valence electrons; 2 are used for bonding with Hydrogen, leaving
4 electrons or 2 lone pairs.
,3. What is the correct name for the compound FeCl3?
A. Iron trichloride
B. Iron(II) chloride
C. Ferrous chloride
D. Iron(III) chloride
Answer: D
Rationale: Iron is a transition metal with variable charges. Since Chlorine has a -1 charge,
Iron must be +3 to balance the three chlorides.
4. What is the name of the molecular compound N2O4?
A. Nitrogen oxide
B. Nitrogen tetroxide
C. Dinitrogen tetroxide
D. Dinitrogen quadroxide
Answer: C
Rationale: For molecular compounds, Greek prefixes are used: ‘di-’ for two and ‘tetra-’ for
four.
5. Which of the following elements is an exception to the octet rule and can
have an expanded octet?
A. Carbon
B. Phosphorus
C. Oxygen
D. Nitrogen
Answer: B
Rationale: Elements in the third period and below, such as Phosphorus, have d-orbitals
that allow them to hold more than 8 electrons.
, 6. What is the correct formula for Magnesium phosphate?
A. MgPO4
B. Mg2PO4
C. Mg3PO4
D. Mg3(PO4)2
Answer: D
Rationale: Magnesium has a +2 charge and phosphate (PO4) has a -3 charge; to balance,
we need three Mg and two PO4.
7. A covalent bond where electrons are shared unequally is called:
A. Nonpolar covalent
B. Coordinate covalent
C. Ionic
D. Polar covalent
Answer: D
Rationale: A polar covalent bond occurs when there is a difference in electronegativity
between the two atoms, causing unequal sharing.
8. What is the formal charge of the Nitrogen atom in the ammonium ion
(NH4+)?
A. 0
B. -1
C. +1
D. +2
Answer: C
Rationale: Formal charge = Valence electrons - (lone pair electrons + 1/2 bonding
electrons). For N: 5 - (0 + 4) = +1.
