Chemical Bonding Quiz
Questions: 16 · 10 minutes
1. Which expression correctly calculates the formal charge on an atom in a Lewis structure?
Valence electrons + nonbonding electrons − all bonding electrons
Valence electrons − nonbonding electrons − half the bonding electrons
Valence electrons − all electrons shown around the atom
Nonbonding electrons − valence electrons + half the bonding electrons
2. What does resonance imply about the three nitrogen–oxygen bonds in the nitrate ion, NO₃⁻?
All three are equivalent, with bond character intermediate between single and double bonds.
All three are identical single bonds with a bond order of exactly 1.
One bond remains permanently double while the other two remain permanently single.
One is a triple bond and the other two have no shared electrons.
3. Which molecule is a common exception to the octet rule because its central atom has fewer than eight electrons around it?
NH₃
CH₄
BF₃
H₂O
4. In the usual Lewis structure of the ammonium ion, NH₄⁺, what is the formal charge on nitrogen?
A positive-one formal charge
A negative-one formal charge
A positive-two formal charge
A neutral formal charge of zero
5. In a standard Lewis structure of H₂O, how many lone pairs are shown on the oxygen atom?
One lone pair
Two lone pairs
Three lone pairs
Four lone pairs
6. Magnesium forms Mg²⁺ ions, and oxygen forms O²⁻ ions. What is the electrically neutral formula of their compound?
Mg₂O, containing two magnesium ions for each oxide ion
MgO, containing magnesium and oxide ions in a one-to-one ratio
MgO₂, containing one magnesium ion for every two oxide ions
Mg₂O₃, containing two magnesium ions for every three oxide ions
7. Which pair of atoms is expected to form a nonpolar covalent bond?
Chlorine and chlorine
Hydrogen and chlorine
Sodium and chlorine
Magnesium and oxygen
8. Which model best describes metallic bonding in a piece of copper?
Positive metal ions are attracted to delocalized valence electrons.
Copper atoms exchange electrons to form alternating positive and negative ions.
Each electron pair is confined between exactly two copper atoms.
Neutral molecules are connected by hydrogen bonds.
9. An ion contains 12 protons and 10 electrons. What is its net charge?
A net charge of negative two
A neutral net charge of zero
A net charge of positive two
A net charge of positive one
10. Consider a C–C single bond, a C=C double bond, and a C≡C triple bond. Which is generally the shortest?
The C–C single bond
The C=C double bond
They are generally equal in length because the same elements are bonded.
The C≡C triple bond
11. What happens to valence electrons when a typical covalent bond forms?
They move permanently from the less electronegative atom to the more electronegative atom.
They become delocalized throughout a metallic lattice.
They enter the atomic nuclei and reduce nuclear charge.
They are shared between bonded atoms.
12. Each C=O bond in carbon dioxide is polar. Why is a CO₂ molecule nevertheless nonpolar overall?
The oxygen atoms lose their lone pairs when the molecule forms.
Carbon and oxygen have identical electronegativities.
Carbon dioxide contains ionic rather than covalent bonds.
Its linear shape makes the two equal bond dipoles point in opposite directions and cancel.
13. Based on electronegativity differences, which bond is expected to be the most polar?
N–H
H–Cl
H–F
C–H
14. A student tests sodium chloride as a solid and then as a molten liquid. Which observation is expected?
It conducts as a solid but not when molten because melting breaks all ions apart.
It does not conduct as a solid but conducts when molten because the ions can then move.
It conducts equally well in both states because its electrons move freely like those in a metal.
It conducts in neither state because ionic compounds contain no charged particles.
15. When liquid water becomes water vapor, which attractions are primarily overcome?
The covalent O–H bonds inside each water molecule
Ionic bonds between H⁺ and O²⁻ ions
Hydrogen bonds between separate water molecules
Metallic attractions involving delocalized electrons
16. Which description best explains the bonding in sodium chloride, NaCl?
The atoms are held together mainly by intermolecular attractions.
Sodium and chlorine contribute electrons to a freely moving electron sea.
The atoms share one electron pair equally.
Electrons are transferred, producing oppositely charged ions that attract one another.