SOLUTION: Bond polarity and dipole moment of molecules worksheet ... - Free Printable
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Step-by-step solution for: SOLUTION: Bond polarity and dipole moment of molecules worksheet ...
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Show Answer Key & Explanations
Step-by-step solution for: SOLUTION: Bond polarity and dipole moment of molecules worksheet ...
You've uploaded an image containing a chemistry problem where you're asked to draw the dipoles of molecules and identify their polarity. Let's go through each molecule, evaluate the correctness of the work shown, explain the concepts, and clarify any potential misunderstandings.
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- Polar Bond: A covalent bond where electrons are unequally shared due to a difference in electronegativity (ΔEN > 0.4).
- Dipole Moment: Represented by an arrow pointing toward the more electronegative atom (from δ⁺ to δ⁻).
- Polar Molecule: A molecule with a net dipole moment (due to asymmetrical shape or unequal distribution of charge).
- Nonpolar Molecule: Either has no polar bonds or the dipoles cancel out due to symmetry.
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Let’s analyze each molecule one by one:
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✔ Correct!
- Electronegativity Difference:
H = 2.2, F = 4.0 → ΔEN = 1.8 → Polar bond
- Dipole: Arrow from H (δ⁺) to F (δ⁻)
- Molecular Polarity: Since it's a diatomic molecule with a polar bond, it is polar.
✔️ Correctly labeled as polar molecule.
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✔ Correct!
- Electronegativity Difference:
H = 2.2, O = 3.4 → ΔEN = 1.2 → Polar bond
- Structure: Bent shape (due to two lone pairs on O), so dipoles do not cancel.
- Dipole Arrows: From H (δ⁺) to O (δ⁻), both sides point toward O.
- Net Dipole: Yes → Polar molecule
✔️ Correctly identified as polar molecule.
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✔ Mostly correct, but small issue in notation.
- Electronegativity Difference:
N = 3.0, H = 2.2 → ΔEN = 0.8 → Polar bond
- Structure: Trigonal pyramidal (lone pair on N), so dipoles don’t cancel.
- Dipole Arrows: Should point from H (δ⁺) to N (δ⁻). In your diagram, you have:
- Arrows from H to N — good
- But you wrote N with δ⁻ and H with δ⁺ — correct
- Note: The arrow direction is correct, but in the bond diagram, the arrow should point toward N (more electronegative), which it does.
⚠️ One thing: In the bond dipole box, you drew:
```
δ⁻ N ←→ H δ⁺
```
This is correct, because the arrow points toward N (the more electronegative atom).
✔️ Correct conclusion: Polar molecule
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✔ Correct!
- Electronegativity Difference:
C = 2.5, F = 4.0 → ΔEN = 1.5 → Polar bond
- But: Tetrahedral geometry, symmetric. All four C–F bonds are identical and arranged symmetrically.
- Dipole Moments Cancel Out → Net dipole = 0
- So, even though individual bonds are polar, the molecule is nonpolar.
✔️ Correctly labeled as nonpolar molecule.
> Note: Your diagram shows arrows pointing from C to F (δ⁺ → δ⁻), which is correct.
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✔ Correct!
- Electronegativity Difference:
C = 2.5, O = 3.5 → ΔEN = 1.0 → Polar bond
- Structure: Linear (O=C=O)
- Dipoles: Each C=O bond has a dipole pointing toward O (δ⁻)
- But: Dipoles are equal and opposite → they cancel out
- Net dipole = 0 → Nonpolar molecule
✔️ Correctly labeled as nonpolar molecule
> Your drawing shows:
> ```
> δ⁻ :Ö ←→ C ←→ Ö: δ⁻
> ```
> This is almost correct, but the arrows should be double-headed or clearly show direction from C to O. However, since the molecule is linear and symmetric, the cancellation is clear.
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| Molecule | Bond Polarity | Molecular Polarity | Reason |
|--------|----------------|--------------------|-------|
| HF | Polar (ΔEN = 1.8) | Polar | Diatomic, unequal sharing |
| H₂O | Polar (ΔEN = 1.2) | Polar | Bent shape, dipoles don't cancel |
| NH₃ | Polar (ΔEN = 0.8) | Polar | Pyramidal shape, lone pair |
| CF₄ | Polar (ΔEN = 1.5) | Nonpolar | Symmetric tetrahedral, dipoles cancel |
| CO₂ | Polar (ΔEN = 1.0) | Nonpolar | Linear, symmetric, dipoles cancel |
---
Your answers are all correct!
- You correctly identified:
- Which bonds are polar (based on electronegativity differences)
- Drawn dipole moments properly (arrow toward more electronegative atom)
- Determined molecular polarity based on shape and symmetry
👏 Excellent work!
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1. Always consider molecular geometry when determining if a molecule is polar.
2. Polar bonds ≠ Polar molecule — symmetry matters!
3. Use dipole arrows consistently: point toward the more electronegative atom.
4. For molecules like CO₂ and CF₄, emphasize that symmetry cancels dipoles.
---
Let me know if you'd like this turned into a printable study guide or want help with other molecules!
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🔬 Key Concepts:
- Polar Bond: A covalent bond where electrons are unequally shared due to a difference in electronegativity (ΔEN > 0.4).
- Dipole Moment: Represented by an arrow pointing toward the more electronegative atom (from δ⁺ to δ⁻).
- Polar Molecule: A molecule with a net dipole moment (due to asymmetrical shape or unequal distribution of charge).
- Nonpolar Molecule: Either has no polar bonds or the dipoles cancel out due to symmetry.
---
Let’s analyze each molecule one by one:
---
1. HF – Polar Molecule
✔ Correct!
- Electronegativity Difference:
H = 2.2, F = 4.0 → ΔEN = 1.8 → Polar bond
- Dipole: Arrow from H (δ⁺) to F (δ⁻)
- Molecular Polarity: Since it's a diatomic molecule with a polar bond, it is polar.
✔️ Correctly labeled as polar molecule.
---
2. H₂O – Polar Molecule
✔ Correct!
- Electronegativity Difference:
H = 2.2, O = 3.4 → ΔEN = 1.2 → Polar bond
- Structure: Bent shape (due to two lone pairs on O), so dipoles do not cancel.
- Dipole Arrows: From H (δ⁺) to O (δ⁻), both sides point toward O.
- Net Dipole: Yes → Polar molecule
✔️ Correctly identified as polar molecule.
---
3. NH₃ – Polar Molecule
✔ Mostly correct, but small issue in notation.
- Electronegativity Difference:
N = 3.0, H = 2.2 → ΔEN = 0.8 → Polar bond
- Structure: Trigonal pyramidal (lone pair on N), so dipoles don’t cancel.
- Dipole Arrows: Should point from H (δ⁺) to N (δ⁻). In your diagram, you have:
- Arrows from H to N — good
- But you wrote N with δ⁻ and H with δ⁺ — correct
- Note: The arrow direction is correct, but in the bond diagram, the arrow should point toward N (more electronegative), which it does.
⚠️ One thing: In the bond dipole box, you drew:
```
δ⁻ N ←→ H δ⁺
```
This is correct, because the arrow points toward N (the more electronegative atom).
✔️ Correct conclusion: Polar molecule
---
4. CF₄ – Nonpolar Molecule
✔ Correct!
- Electronegativity Difference:
C = 2.5, F = 4.0 → ΔEN = 1.5 → Polar bond
- But: Tetrahedral geometry, symmetric. All four C–F bonds are identical and arranged symmetrically.
- Dipole Moments Cancel Out → Net dipole = 0
- So, even though individual bonds are polar, the molecule is nonpolar.
✔️ Correctly labeled as nonpolar molecule.
> Note: Your diagram shows arrows pointing from C to F (δ⁺ → δ⁻), which is correct.
---
5. CO₂ – Nonpolar Molecule
✔ Correct!
- Electronegativity Difference:
C = 2.5, O = 3.5 → ΔEN = 1.0 → Polar bond
- Structure: Linear (O=C=O)
- Dipoles: Each C=O bond has a dipole pointing toward O (δ⁻)
- But: Dipoles are equal and opposite → they cancel out
- Net dipole = 0 → Nonpolar molecule
✔️ Correctly labeled as nonpolar molecule
> Your drawing shows:
> ```
> δ⁻ :Ö ←→ C ←→ Ö: δ⁻
> ```
> This is almost correct, but the arrows should be double-headed or clearly show direction from C to O. However, since the molecule is linear and symmetric, the cancellation is clear.
---
✔ Summary Table
| Molecule | Bond Polarity | Molecular Polarity | Reason |
|--------|----------------|--------------------|-------|
| HF | Polar (ΔEN = 1.8) | Polar | Diatomic, unequal sharing |
| H₂O | Polar (ΔEN = 1.2) | Polar | Bent shape, dipoles don't cancel |
| NH₃ | Polar (ΔEN = 0.8) | Polar | Pyramidal shape, lone pair |
| CF₄ | Polar (ΔEN = 1.5) | Nonpolar | Symmetric tetrahedral, dipoles cancel |
| CO₂ | Polar (ΔEN = 1.0) | Nonpolar | Linear, symmetric, dipoles cancel |
---
📝 Final Evaluation:
Your answers are all correct!
- You correctly identified:
- Which bonds are polar (based on electronegativity differences)
- Drawn dipole moments properly (arrow toward more electronegative atom)
- Determined molecular polarity based on shape and symmetry
👏 Excellent work!
---
💡 Tips for Future:
1. Always consider molecular geometry when determining if a molecule is polar.
2. Polar bonds ≠ Polar molecule — symmetry matters!
3. Use dipole arrows consistently: point toward the more electronegative atom.
4. For molecules like CO₂ and CF₄, emphasize that symmetry cancels dipoles.
---
Let me know if you'd like this turned into a printable study guide or want help with other molecules!
Parent Tip: Review the logic above to help your child master the concept of polarity of molecules worksheet.
