Free Practice Quiz Question List

3 Chemical Bonding and Lewis Structures Online Quiz Questions

Use this free practice quiz with 30 questions to review 3 Chemical Bonding and Lewis Structures, test your knowledge, and prepare for your next test or exam.

30 questions

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1 point

What does the formula NaCl represent in solid sodium chloride?

A
Each solid contains separate NaCl molecules.
B
The solid contains sodium and chloride ions in a 1:1 ratio.
C
The solid contains equal numbers of sodium atoms and chlorine atoms joined in pairs.
D
Each sodium ion is attracted only to one chloride ion.

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1 point

In the polar covalent bond H–Cl, which partial-charge assignment is correct?

A
Hydrogen is δ− and chlorine is δ+.
B
Both atoms have full ionic charges.
C
Hydrogen is δ+ and chlorine is δ−.
D
Both atoms have no partial charges because the bond is covalent.

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1 point

How many total valence electrons must be included when drawing a Lewis structure for neutral CO₂?

A
16
B
12
C
18
D
20

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1 point

When choosing a usual Lewis-structure skeleton for HCN, which atom should be central, and why?

A
Place hydrogen in the center because it has the fewest valence electrons.
B
Place carbon in the center because it is the least electronegative atom other than hydrogen.
C
Place nitrogen in the center because it is the most electronegative atom.
D
Place either hydrogen or nitrogen in the center; the choice does not depend on electronegativity.

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1 point

After connecting atoms with single bonds and completing terminal atoms' octets, what should you do with any remaining electrons in the usual Lewis-structure procedure?

A
Immediately form double bonds between every pair of atoms.
B
Remove any remaining electrons so the central atom has exactly eight.
C
Place any remaining electrons on the central atom.
D
Add one electron to each terminal atom, regardless of its octet.

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1 point

An oxygen atom has 6 valence electrons, 4 nonbonding electrons, and 4 bonding electrons. Using formal-charge bookkeeping, what is its formal charge?

A
0
B
+1
C
−1
D
+2

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1 point

Which statement correctly describes hydrogen when applying electron-counting rules to Lewis structures?

A
Hydrogen must have eight electrons whenever it is bonded.
B
The octet rule applies without exception to all atoms in a Lewis structure.
C
Hydrogen is an exception because it needs no electrons around it.
D
Hydrogen follows a duet rule rather than an octet rule.

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1 point

Which description correctly identifies how resonance structures are related and how they are conventionally connected?

A
They show different arrangements of atoms in equilibrium and use an equilibrium arrow.
B
They show the same arrangement of atoms with different electron placements and use a resonance arrow.
C
They show the molecule switching rapidly between distinct structures and use a reaction arrow.
D
They differ only in the positions of nuclei and use a single-headed arrow.

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1 point

What does the resonance-hybrid model predict about the three N–O bonds in NO₃⁻?

A
The ion has one permanently localized N=O double bond and two distinct N–O single bonds.
B
The ion rapidly switches among three separate structures, each with different bond lengths.
C
The ion has three equivalent N–O bonds, each intermediate in character between a single and a double bond.
D
The ion has three N–O bonds that are all equivalent to double bonds.

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1 point

For carbon–carbon bonds, how does a triple bond generally compare with a double bond in length and strength?

A
The triple bond is generally shorter and stronger than the double bond.
B
The triple bond is generally longer and weaker than the double bond.
C
The triple bond is generally shorter but weaker than the double bond.
D
The two bonds must have the same length and strength because they join the same elements.

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1 point

What does bond energy refer to?

A
The energy released whenever two atoms form a bond in a solid.
B
The energy needed to separate an ionic solid into isolated ion pairs.
C
The average distance between nuclei in bonded atoms.
D
The energy required to break a specified bond in gaseous molecules.

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1 point

Which description best matches lattice energy in an ionic solid?

A
The energy needed to break one isolated ion pair in the gaseous state.
B
The collective attraction among ions in the ionic solid.
C
The energy required to break a specified covalent bond in a gas.
D
The average distance between neighboring ion nuclei.

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1 point

How does a carbon–carbon triple bond generally compare with a carbon–carbon double bond?

A
The double bond is generally shorter and stronger than the triple bond.
B
The two bonds have the same length and strength because they involve the same atoms.
C
The triple bond is generally longer and weaker than the double bond.
D
The triple bond is generally shorter and stronger than the double bond.

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1 point

Two Lewis structures satisfy the same overall electron count and octet requirements. Which guideline can help identify the more favorable structure?

A
Prefer the structure with the most formal charges, regardless of their values.
B
Prefer a structure that places negative formal charge on the least electronegative atom.
C
Prefer a reasonable structure that minimizes formal charges and places negative formal charge on more electronegative atoms when possible.
D
Prefer the structure with the greatest number of bonds, even if its electron count is incorrect.

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1 point

Which statement correctly distinguishes bond energy from lattice energy?

A
Bond energy is for breaking a specified bond in gaseous molecules; lattice energy describes collective ionic attraction in a solid.
B
Bond energy describes the entire ionic lattice; lattice energy is the energy to break a covalent bond in a gas.
C
Bond energy and lattice energy both refer only to isolated pairs of ions in a solid.
D
Bond energy is the distance between nuclei; lattice energy is the number of shared electron pairs.

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1 point

In a polar covalent H–Cl bond, which assignment of partial charges is correct?

A
Hydrogen is δ− and chlorine is δ+.
B
Both atoms have no partial charges because the bond is covalent.
C
Hydrogen is δ+ and chlorine is δ−.
D
Both atoms are full ions with charges H⁺ and Cl⁻ in the covalent bond.

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1 point

How many electron pairs do the two atoms share in an O₂ molecule, and what bond does this represent?

A
One shared electron pair, represented by a single bond.
B
Two shared electron pairs, represented by a double bond.
C
Three shared electron pairs, represented by a triple bond.
D
No shared electron pairs; the atoms are held together by ionic attraction.

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1 point

Which Lewis structure correctly represents neutral CO₂ while giving each atom an octet?

A
O=C=O, with two lone pairs on each oxygen and none on carbon.
B
O–C–O, with only single bonds and an incomplete octet on carbon.
C
O≡C–O, with a triple bond to one oxygen and a single bond to the other.
D
O=C–O, with one double bond and one single bond in a neutral molecule.

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1 point

In the Lewis structure O=C=O, what is the formal charge on the carbon atom?

A
0
B
−1
C
+1
D
+2

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1 point

Three valid resonance structures for NO₃⁻ place the N=O double bond on different oxygen atoms. What does this imply about the actual nitrate ion?

A
The ion rapidly switches among three structures, each with one permanently distinct N=O bond.
B
Only one oxygen atom carries the negative charge in the actual ion.
C
The actual ion is a delocalized hybrid with three equivalent N–O bonds intermediate in character between single and double bonds.
D
The three drawings have different arrangements of atoms and therefore represent different ions.

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1 point

Why is a bonded arrangement of atoms generally more stable than the same atoms separated?

A
The bonded arrangement must contain more energy than the separated atoms.
B
The bonded arrangement is generally lower in energy and more stable.
C
Bond formation prevents the atoms from attracting one another.
D
The separated atoms always have the lowest possible energy.

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1 point

Which statement best describes how ionic and covalent bonding models relate to one another?

A
Every bond is either completely ionic or completely covalent, with no intermediate cases.
B
The two models describe unrelated phenomena and cannot be compared.
C
Ionic and covalent bonding are best treated as ends of a continuum.
D
A bond's classification depends only on how many atoms are present.

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1 point

A student sees a formal charge assigned to an atom in a Lewis structure. What is the most accurate interpretation of that value?

A
It is an electron-bookkeeping value based on an equal-sharing convention, not necessarily the atom's actual charge.
B
It directly measures the exact amount of electron density on an atom.
C
It is the partial charge caused by unequal attraction for bonding electrons.
D
It gives the energy required to break a bond to that atom.

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1 point

When checking the formal charges in a Lewis structure for a polyatomic ion, which condition should be satisfied?

A
The formal charges must all be zero, regardless of the species' charge.
B
Their sum must equal the number of atoms in the species.
C
Their sum must equal the number of bonds in the structure.
D
Their sum must equal the overall charge of the species.

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1 point

Which statement most accurately describes the scope of the octet rule?

A
It applies without exception to every atom in every molecule.
B
It is a useful guide, especially for second-row elements such as carbon, nitrogen, oxygen, and fluorine, but it is not universal.
C
It applies only to hydrogen and helium.
D
It is a rule for determining how many atoms a molecule must contain.

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1 point

A species has an odd total number of electrons. What consequence follows for its electron pairing?

A
An odd total guarantees that every atom has a complete octet.
B
An odd total means the species cannot contain any bonds.
C
At least one electron cannot be paired with another electron.
D
An odd total changes the species into an ionic crystal.

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1 point

A proposed Lewis structure gives its central atom fewer than eight electrons. What is the best conclusion based on the limitations of the octet rule?

A
It is not automatically invalid, because some valid structures have a central atom with fewer than eight electrons.
B
It must be invalid, because every atom in every structure must have exactly eight electrons.
C
It must be an ion, because neutral molecules cannot have such structures.
D
It is valid only if every terminal atom also has fewer than eight electrons.

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1 point

Which statement reflects a recognized limitation of applying the octet rule to every Lewis structure?

A
A central atom can never have more than eight electrons in a valid structure.
B
More than eight electrons always means the atom count was entered incorrectly.
C
Only terminal atoms can ever have more than eight electrons.
D
Some valid structures have central atoms with more than eight electrons.

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1 point

In Lewis-structure notation, what does a double-headed resonance arrow indicate?

A
It shows that one structure is changing into a different chemical species at equilibrium.
B
It links alternative Lewis structures that represent the same species.
C
It indicates that the atoms are moving to new positions in each drawing.
D
It marks a reversible transfer of atoms between two molecules.

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1 point

When comparing possible Lewis structures, how should the preference for fewer formal charges be used?

A
Choose the structure with the most formal charges, even if its electron count is wrong.
B
Choose whichever structure places every negative formal charge on the least electronegative atom.
C
Treat fewer formal charges as a useful preference, while still checking electron counts and octets where applicable.
D
Ignore electron counts whenever one structure has fewer formal charges.