Lewis Structure Quiz
Questions: 16 · 10 minutes
1. Nitric oxide, NO, cannot give both atoms conventional octets because it has an odd number of valence electrons. What is that total?
11 valence electrons
12 valence electrons
13 valence electrons
10 valence electrons
2. In the lowest-formal-charge Lewis structure of ClO⁻, the atoms are joined by a single bond. Which atom carries the −1 formal charge?
The chlorine atom
The oxygen atom
The charge is divided equally between chlorine and oxygen
Neither atom carries it; the charge appears only outside the brackets
3. Which species has a standard Lewis structure in which the central atom has an expanded octet?
CO₂
SF₆
NH₃
BF₃
4. How many valence electrons should be placed in the Lewis structure of NO₃⁻?
23 valence electrons
24 valence electrons
18 valence electrons
32 valence electrons
5. After the two O–H single bonds are drawn in H₂O, how many lone pairs should be placed on oxygen?
No lone pairs
One lone pair
Three lone pairs
Two lone pairs
6. Which bonding pattern for CO₂ gives all three atoms complete octets and formal charges of zero?
Two single bonds: O–C–O
A triple bond to one oxygen and a single bond to the other: O≡C–O
Two double bonds, one to each oxygen: O=C=O
Two triple bonds, one to each oxygen: O≡C≡O
7. For the Lewis structure [:C≡N:]⁻, what are the formal charges on carbon and nitrogen, respectively?
Carbon has −1; nitrogen has 0
Carbon has +1; nitrogen has −2
Carbon has −1; nitrogen has −1
Carbon has 0; nitrogen has −1
8. In the Lewis structure of NH₄⁺, nitrogen forms four single bonds and has no lone pairs. What is its formal charge?
A positive-one formal charge
A neutral formal charge of zero
A negative-one formal charge
A positive-two formal charge
9. Two valid resonance structures of ozone, O₃, differ primarily in which feature?
The order in which the three oxygen atoms are connected
The identity of the central atom
The total number of valence electrons
The placement of the double bond, lone-pair electrons, and formal charges
10. In the resonance hybrid of CO₃²⁻, the three C–O bonds are equivalent. What is their average bond order?
An average bond order of 1
An average bond order of 1.25
An average bond order of 1.33, or 4/3
An average bond order of 1.5
11. Which expression correctly calculates the formal charge on an atom in a Lewis structure?
Valence electrons − bonding electrons − lone pairs
Valence electrons − nonbonding electrons − half of the bonding electrons
Valence electrons + nonbonding electrons − bonding electrons
Valence electrons − half of the nonbonding electrons − bonding electrons
12. Which description correctly accounts for all 10 valence electrons in N₂ while giving each nitrogen an octet?
A double bond with two lone pairs on each nitrogen
A triple bond with no lone pairs on either nitrogen
A single bond with three lone pairs on each nitrogen
A triple bond with one lone pair on each nitrogen
13. How many total valence electrons must be included when drawing the Lewis structure of CO₂?
18 electrons
12 electrons
16 electrons
22 electrons
14. The Lewis structure of formaldehyde, H₂CO, contains two C–H bonds and one C=O bond. What electron-group geometry does this imply around carbon?
Trigonal planar
Tetrahedral
Bent
Linear
15. Which molecule has a commonly accepted Lewis structure in which the central atom has fewer than eight electrons?
CH₄
NH₃
H₂O
BF₃
16. Before adding multiple bonds or lone pairs, which atomic skeleton should be used for HCN?
Hydrogen bonded to nitrogen, followed by carbon: H–N–C
Carbon bonded to hydrogen, followed by nitrogen: C–H–N
Hydrogen bonded to carbon, followed by nitrogen: H–C–N
A three-membered ring containing H, C, and N