WGU D425 Introduction to
Chemistry | Lewis
Structure Practice
Questions, PA & OA Exam
Review
|Guaranteed success|
,Draw the Lewis structure for NH₃ Total valence electrons = 8. N in middle, H outside. Single bonds N-H. 2
leftover electrons → 1 lone pair on N
Draw the Lewis structure for CH₄ Total valence electrons = 8. C in middle, H outside. Single bonds C-H. No lone
pairs
Draw the Lewis structure for O₂ Total valence electrons = 12. Single bond O-O leaves octets incomplete →
make double bond O=O. Each O has 8 electrons
Draw the Lewis structure for HCN Total valence electrons = 10. H-C≡N. Triple bond C≡N, single bond H-C. C and
N have octets, H has 2
Draw the Lewis structure for H₂CO (formaldehyde) Total valence electrons = 12. C in middle, O and H outside. C=O double bond,
C-H single bonds. Octets satisfied
Draw the Lewis structure for NO (nitric oxide) Total valence electrons = 1. N=O with one lone electron on N.
Draw the Lewis structure for H₂S Total valence electrons = 8. S in middle, H outside. Single bonds H-S-H.
Remaining 4 electrons → 2 lone pairs on S
, Draw the Lewis structure for C₂H₄ (ethylene) Total valence electrons = 12. C=C double bond in middle. Each C has 2 H single
bonds. Octets satisfied
Draw the Lewis structure for CO (carbon monoxide) Total valence electrons = 10. Triple bond between C≡O. C has a lone pair, O has
a lone pair. Formal charges: C (-1), O (+1)
Draw the Lewis structure for SO₂ (sulfur dioxide) and Total valence electrons = 18. S in middle, O on sides. One S=O double bond and
show resonance one S-O single bond with lone pairs. Resonance: the double bond can switch
to the other O
Draw the Lewis structure for NO₂⁻ (nitrite ion) Total valence electrons = 18 (extra 1 for negative charge). N in middle, O on
sides. One double bond, one single bond with lone pairs. Resonance: double
bond can move between the two O atoms
Draw the Lewis structure for C₂H₂ (acetylene) Total valence electrons = 10. Triple bond C≡C in middle, each C bonded to 1 H.
Each C has 2 electrons in bonds + triple bond → octet satisfied
Draw the Lewis structure for O₃ (ozone) and indicate Total valence electrons = 18. O in the middle forms one double bond with one
resonance O, single bond with the other. Lone pairs on outer O's. Resonance: double
bond can flip between the two outer O atoms
Draw the Lewis structure for C₂H₄O Total valence electrons = 20. C-C backbone. First C (CH₃) single bonded to H's,
second C double bonded to O, single bonded to H. Lone pairs on O
Chemistry | Lewis
Structure Practice
Questions, PA & OA Exam
Review
|Guaranteed success|
,Draw the Lewis structure for NH₃ Total valence electrons = 8. N in middle, H outside. Single bonds N-H. 2
leftover electrons → 1 lone pair on N
Draw the Lewis structure for CH₄ Total valence electrons = 8. C in middle, H outside. Single bonds C-H. No lone
pairs
Draw the Lewis structure for O₂ Total valence electrons = 12. Single bond O-O leaves octets incomplete →
make double bond O=O. Each O has 8 electrons
Draw the Lewis structure for HCN Total valence electrons = 10. H-C≡N. Triple bond C≡N, single bond H-C. C and
N have octets, H has 2
Draw the Lewis structure for H₂CO (formaldehyde) Total valence electrons = 12. C in middle, O and H outside. C=O double bond,
C-H single bonds. Octets satisfied
Draw the Lewis structure for NO (nitric oxide) Total valence electrons = 1. N=O with one lone electron on N.
Draw the Lewis structure for H₂S Total valence electrons = 8. S in middle, H outside. Single bonds H-S-H.
Remaining 4 electrons → 2 lone pairs on S
, Draw the Lewis structure for C₂H₄ (ethylene) Total valence electrons = 12. C=C double bond in middle. Each C has 2 H single
bonds. Octets satisfied
Draw the Lewis structure for CO (carbon monoxide) Total valence electrons = 10. Triple bond between C≡O. C has a lone pair, O has
a lone pair. Formal charges: C (-1), O (+1)
Draw the Lewis structure for SO₂ (sulfur dioxide) and Total valence electrons = 18. S in middle, O on sides. One S=O double bond and
show resonance one S-O single bond with lone pairs. Resonance: the double bond can switch
to the other O
Draw the Lewis structure for NO₂⁻ (nitrite ion) Total valence electrons = 18 (extra 1 for negative charge). N in middle, O on
sides. One double bond, one single bond with lone pairs. Resonance: double
bond can move between the two O atoms
Draw the Lewis structure for C₂H₂ (acetylene) Total valence electrons = 10. Triple bond C≡C in middle, each C bonded to 1 H.
Each C has 2 electrons in bonds + triple bond → octet satisfied
Draw the Lewis structure for O₃ (ozone) and indicate Total valence electrons = 18. O in the middle forms one double bond with one
resonance O, single bond with the other. Lone pairs on outer O's. Resonance: double
bond can flip between the two outer O atoms
Draw the Lewis structure for C₂H₄O Total valence electrons = 20. C-C backbone. First C (CH₃) single bonded to H's,
second C double bonded to O, single bonded to H. Lone pairs on O
