Worksheet for drawing Lewis structures of molecular compounds and acids.
Worksheet titled "Drawing Lewis structures" with a table listing seven compounds or acids, including phosphorus trifluoride, acetic acid, silicon tetrahydride, oxygen dichloride, nitric acid, hydrochloric acid, and dinitrogen tetrachloride, each with columns for molecular formula and Lewis structure.
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Step-by-step solution for: Worksheet- Drawing Lewis structures
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Show Answer Key & Explanations
Step-by-step solution for: Worksheet- Drawing Lewis structures
Sure! Let’s solve this worksheet step by step. For each compound, I’ll provide:
1. Molecular formula — based on standard chemical nomenclature.
2. Lewis structure — explained in text (since I can’t draw images, I’ll describe it clearly with atom connections, bonds, and lone pairs).
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- Molecular formula: PF₃
- Lewis structure explanation:
- Phosphorus (P) is the central atom (less electronegative than F).
- P has 5 valence electrons; each F has 7.
- Total valence electrons = 5 + 3×7 = 26.
- P forms single bonds with each of the 3 F atoms → uses 6 electrons (3 bonds × 2 electrons).
- Remaining 20 electrons go to lone pairs: each F gets 3 lone pairs (6 electrons each → 18 total), and P gets 1 lone pair (2 electrons).
- Structure: P in center, bonded to 3 F atoms, each F has 3 lone pairs, P has 1 lone pair.
- Shape: trigonal pyramidal.
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- Molecular formula: CH₃COOH or C₂H₄O₂
- Lewis structure explanation:
- Two carbon atoms: one methyl group (CH₃–), one carboxyl group (–COOH).
- Central C (carbonyl) double-bonded to O, single-bonded to OH, and single-bonded to CH₃.
- The OH oxygen has 2 lone pairs; carbonyl O has 2 lone pairs.
- CH₃ group: C bonded to 3 H atoms and the carbonyl C.
- Total valence electrons: 24 (C=4×2=8, H=1×4=4, O=6×2=12 → total 24).
- Structure:
H
|
H — C — C(=O) — O — H
|
H
Lone pairs: double-bonded O has 2 lone pairs, single-bonded O (in OH) has 2 lone pairs.
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- Molecular formula: SiH₄
- Lewis structure explanation:
- Silicon (Si) is central atom; bonded to 4 H atoms.
- Si has 4 valence electrons; each H has 1 → total = 4 + 4×1 = 8 valence electrons.
- All 8 electrons are used in 4 single bonds (Si–H).
- No lone pairs on Si or H.
- Tetrahedral geometry.
- Structure: Si in center, 4 H atoms around it, each connected by a single bond.
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- Molecular formula: OCl₂
- Lewis structure explanation:
- Oxygen is central atom (less electronegative than Cl? Actually, O is more electronegative, but it’s still central because it can form multiple bonds — here, it doesn’t need to).
- O has 6 valence electrons; each Cl has 7 → total = 6 + 2×7 = 20 valence electrons.
- O forms single bonds with each Cl → 4 electrons used.
- Remaining 16 electrons → each Cl gets 3 lone pairs (6 electrons each → 12 total), O gets 2 lone pairs (4 electrons).
- Structure: O in center, bonded to two Cl atoms. Each Cl has 3 lone pairs, O has 2 lone pairs.
- Bent molecular geometry (like water).
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- Molecular formula: HNO₃
- Lewis structure explanation:
- Central N atom bonded to 3 O atoms and one OH group.
- One O is double-bonded to N; two O atoms are single-bonded (one of which is bonded to H).
- Total valence electrons: H=1, N=5, O×3=18 → total 24.
- Structure:
O
||
O — N — O — H
|
(lone pairs)
- Double-bonded O: 2 lone pairs.
- Single-bonded O (not attached to H): 3 lone pairs (and negative formal charge).
- O in OH: 2 lone pairs.
- N has no lone pairs.
- Resonance exists — the double bond can rotate among the three O atoms, but in the most stable structure, the H is attached to an O with a single bond to N.
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- Molecular formula: HCl
- Lewis structure explanation:
- Simple diatomic molecule.
- H has 1 valence electron, Cl has 7 → total 8 valence electrons.
- One single bond between H and Cl → 2 electrons used.
- Remaining 6 electrons go to Cl as 3 lone pairs.
- Structure: H — Cl with 3 lone pairs on Cl.
- Linear (but since only two atoms, no real shape).
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- Molecular formula: N₂Cl₄
- Lewis structure explanation:
- Two N atoms bonded together; each N bonded to two Cl atoms.
- Total valence electrons: N×2=10, Cl×4=28 → total 38.
- Central N–N single bond → 2 electrons.
- Each N bonded to 2 Cl → 4 more bonds → 8 electrons → total bonds use 10 electrons.
- Remaining 28 electrons → each Cl gets 3 lone pairs (6 electrons × 4 Cl = 24), each N gets 1 lone pair (2 electrons × 2 N = 4).
- Structure: Cl₂N–NCl₂, with each N having one lone pair, each Cl having 3 lone pairs.
- Geometry around each N: trigonal pyramidal.
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✔ Summary Table for Worksheet Completion
| Compound Name | Molecular Formula | Lewis Structure Description |
|-------------------------|-------------------|---------------------------------------------------------------------------------------------|
| 1. phosphorus trifluoride | PF₃ | P central, bonded to 3 F; P has 1 lone pair, each F has 3 lone pairs. |
| 2. acetic acid | CH₃COOH or C₂H₄O₂ | CH₃–C(=O)–OH; carbonyl O double bond, OH single bond; lone pairs on O atoms. |
| 3. silicon tetrahydride | SiH₄ | Si central, bonded to 4 H; no lone pairs. |
| 4. oxygen dichloride | OCl₂ | O central, bonded to 2 Cl; O has 2 lone pairs, each Cl has 3 lone pairs. |
| 5. nitric acid | HNO₃ | N central, double bond to one O, single bonds to two O (one bonded to H); lone pairs on O. |
| 6. hydrochloric acid | HCl | H–Cl single bond; Cl has 3 lone pairs. |
| 7. dinitrogen tetrachloride | N₂Cl₄ | Cl₂N–NCl₂; N–N single bond; each N has 1 lone pair, each Cl has 3 lone pairs. |
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Let me know if you’d like hand-drawn style ASCII diagrams or help drawing these on paper!
1. Molecular formula — based on standard chemical nomenclature.
2. Lewis structure — explained in text (since I can’t draw images, I’ll describe it clearly with atom connections, bonds, and lone pairs).
---
1. Phosphorus trifluoride
- Molecular formula: PF₃
- Lewis structure explanation:
- Phosphorus (P) is the central atom (less electronegative than F).
- P has 5 valence electrons; each F has 7.
- Total valence electrons = 5 + 3×7 = 26.
- P forms single bonds with each of the 3 F atoms → uses 6 electrons (3 bonds × 2 electrons).
- Remaining 20 electrons go to lone pairs: each F gets 3 lone pairs (6 electrons each → 18 total), and P gets 1 lone pair (2 electrons).
- Structure: P in center, bonded to 3 F atoms, each F has 3 lone pairs, P has 1 lone pair.
- Shape: trigonal pyramidal.
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2. Acetic acid
- Molecular formula: CH₃COOH or C₂H₄O₂
- Lewis structure explanation:
- Two carbon atoms: one methyl group (CH₃–), one carboxyl group (–COOH).
- Central C (carbonyl) double-bonded to O, single-bonded to OH, and single-bonded to CH₃.
- The OH oxygen has 2 lone pairs; carbonyl O has 2 lone pairs.
- CH₃ group: C bonded to 3 H atoms and the carbonyl C.
- Total valence electrons: 24 (C=4×2=8, H=1×4=4, O=6×2=12 → total 24).
- Structure:
H
|
H — C — C(=O) — O — H
|
H
Lone pairs: double-bonded O has 2 lone pairs, single-bonded O (in OH) has 2 lone pairs.
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3. Silicon tetrahydride
- Molecular formula: SiH₄
- Lewis structure explanation:
- Silicon (Si) is central atom; bonded to 4 H atoms.
- Si has 4 valence electrons; each H has 1 → total = 4 + 4×1 = 8 valence electrons.
- All 8 electrons are used in 4 single bonds (Si–H).
- No lone pairs on Si or H.
- Tetrahedral geometry.
- Structure: Si in center, 4 H atoms around it, each connected by a single bond.
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4. Oxygen dichloride
- Molecular formula: OCl₂
- Lewis structure explanation:
- Oxygen is central atom (less electronegative than Cl? Actually, O is more electronegative, but it’s still central because it can form multiple bonds — here, it doesn’t need to).
- O has 6 valence electrons; each Cl has 7 → total = 6 + 2×7 = 20 valence electrons.
- O forms single bonds with each Cl → 4 electrons used.
- Remaining 16 electrons → each Cl gets 3 lone pairs (6 electrons each → 12 total), O gets 2 lone pairs (4 electrons).
- Structure: O in center, bonded to two Cl atoms. Each Cl has 3 lone pairs, O has 2 lone pairs.
- Bent molecular geometry (like water).
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5. Nitric acid
- Molecular formula: HNO₃
- Lewis structure explanation:
- Central N atom bonded to 3 O atoms and one OH group.
- One O is double-bonded to N; two O atoms are single-bonded (one of which is bonded to H).
- Total valence electrons: H=1, N=5, O×3=18 → total 24.
- Structure:
O
||
O — N — O — H
|
(lone pairs)
- Double-bonded O: 2 lone pairs.
- Single-bonded O (not attached to H): 3 lone pairs (and negative formal charge).
- O in OH: 2 lone pairs.
- N has no lone pairs.
- Resonance exists — the double bond can rotate among the three O atoms, but in the most stable structure, the H is attached to an O with a single bond to N.
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6. Hydrochloric acid
- Molecular formula: HCl
- Lewis structure explanation:
- Simple diatomic molecule.
- H has 1 valence electron, Cl has 7 → total 8 valence electrons.
- One single bond between H and Cl → 2 electrons used.
- Remaining 6 electrons go to Cl as 3 lone pairs.
- Structure: H — Cl with 3 lone pairs on Cl.
- Linear (but since only two atoms, no real shape).
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7. Dinitrogen tetrachloride
- Molecular formula: N₂Cl₄
- Lewis structure explanation:
- Two N atoms bonded together; each N bonded to two Cl atoms.
- Total valence electrons: N×2=10, Cl×4=28 → total 38.
- Central N–N single bond → 2 electrons.
- Each N bonded to 2 Cl → 4 more bonds → 8 electrons → total bonds use 10 electrons.
- Remaining 28 electrons → each Cl gets 3 lone pairs (6 electrons × 4 Cl = 24), each N gets 1 lone pair (2 electrons × 2 N = 4).
- Structure: Cl₂N–NCl₂, with each N having one lone pair, each Cl having 3 lone pairs.
- Geometry around each N: trigonal pyramidal.
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✔ Summary Table for Worksheet Completion
| Compound Name | Molecular Formula | Lewis Structure Description |
|-------------------------|-------------------|---------------------------------------------------------------------------------------------|
| 1. phosphorus trifluoride | PF₃ | P central, bonded to 3 F; P has 1 lone pair, each F has 3 lone pairs. |
| 2. acetic acid | CH₃COOH or C₂H₄O₂ | CH₃–C(=O)–OH; carbonyl O double bond, OH single bond; lone pairs on O atoms. |
| 3. silicon tetrahydride | SiH₄ | Si central, bonded to 4 H; no lone pairs. |
| 4. oxygen dichloride | OCl₂ | O central, bonded to 2 Cl; O has 2 lone pairs, each Cl has 3 lone pairs. |
| 5. nitric acid | HNO₃ | N central, double bond to one O, single bonds to two O (one bonded to H); lone pairs on O. |
| 6. hydrochloric acid | HCl | H–Cl single bond; Cl has 3 lone pairs. |
| 7. dinitrogen tetrachloride | N₂Cl₄ | Cl₂N–NCl₂; N–N single bond; each N has 1 lone pair, each Cl has 3 lone pairs. |
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Let me know if you’d like hand-drawn style ASCII diagrams or help drawing these on paper!
Parent Tip: Review the logic above to help your child master the concept of molecular structure worksheet.
