Worksheet on Polarity and Electronegativity with questions and molecular examples.

Let's go through each question on the Polarity & Electronegativity Worksheet and provide clear, accurate answers with explanations.

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1. How are ionic bonds and covalent bonds different?

Answer:
Ionic bonds involve the complete transfer of electrons from one atom (usually a metal) to another (usually a nonmetal), resulting in the formation of oppositely charged ions that attract each other. Covalent bonds involve the sharing of electrons between two atoms (typically both nonmetals) to achieve stable electron configurations.

Explanation:
- In ionic bonding, there is a large difference in electronegativity (usually > ~3.0), leading to electron transfer.
- In covalent bonding, the electronegativity difference is small (usually < ~1.7), so electrons are shared.

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2. How does a polar covalent bond differ from a covalent bond?

Answer:
A polar covalent bond has an unequal sharing of electrons due to a significant difference in electronegativity between the bonded atoms. A nonpolar covalent bond has an equal or nearly equal sharing of electrons because the atoms have similar electronegativities.

Explanation:
- Polar covalent: Electrons are pulled more toward the more electronegative atom, creating partial charges (δ+ and δ−).
- Nonpolar covalent: Electrons are shared equally; no partial charges.

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3. What does it mean to say a bond is polar?

Answer:
A bond is polar when there is an unequal distribution of electron density between the two atoms involved in the bond, resulting in one end being partially negative (δ⁻) and the other partially positive (δ⁺).

Explanation:
This occurs due to differences in electronegativity. The more electronegative atom attracts the shared electrons more strongly, creating a dipole.

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4. How do electronegativity values help us determine the polarity of a bond?

Answer:
Electronegativity values indicate how strongly an atom attracts electrons in a bond. By comparing the electronegativity values of the two bonded atoms:
- If the difference is large (> ~0.4), the bond is polar covalent or ionic.
- If the difference is small (< ~0.4), the bond is nonpolar covalent.
- The greater the difference, the more polar the bond.

Explanation:
For example, if one atom has much higher electronegativity than the other, it will pull electrons toward itself, creating a polar bond.

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5. For each of the following molecules, label the part that is partially positive (δ+) and partially negative (δ−). If it is nonpolar, write “nonpolar”.

We’ll use standard electronegativity values (Pauling scale):
- H: 2.20
- C: 2.55
- O: 3.44
- Cl: 3.16
- I: 2.66
- Br: 2.96

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#### a. H–Cl
- Electronegativity: H = 2.20, Cl = 3.16 → ΔEN = 0.96 → Polar covalent
- Cl is more electronegative → attracts electrons more → Cl: δ⁻, H: δ⁺

✔ Answer: H–Cl → H(δ+) – Cl(δ−)

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#### b. H–H
- Same atoms → identical electronegativity → ΔEN = 0 → Nonpolar

✔ Answer: nonpolar

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#### c. H–I
- H = 2.20, I = 2.66 → ΔEN = 0.46 → Polar covalent
- I is more electronegative → I gets δ⁻, H gets δ⁺

✔ Answer: H(δ+) – I(δ−)

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#### d. Br–Br
- Same atoms → ΔEN = 0 → Nonpolar

✔ Answer: nonpolar

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#### e. C=O
- C = 2.55, O = 3.44 → ΔEN = 0.89 → Polar covalent
- O is more electronegative → O gets δ⁻, C gets δ⁺

✔ Answer: C(δ+) = O(δ−)

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✔ Final Answers for Question 5:

a. H(δ+) – Cl(δ−)
b. nonpolar
c. H(δ+) – I(δ−)
d. nonpolar
e. C(δ+) = O(δ−)

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