What Is the Difference Between Polar and Nonpolar Bonds?
In covalent bonds, two atoms share electrons. If atoms are identical or have very similar electronegativities, the electron pair is shared equally—a nonpolar bond. If one atom is much more electronegative, it pulls the electrons closer, creating a polar bond with partial positive and negative charges.
Nonpolar bonds share electrons equally (e.g., H–H, Cl–Cl). Polar bonds have unequal sharing (e.g., H–Cl, O–H) because one atom is more electronegative and pulls electron density toward itself.
Step-by-step worked examples
Is the H–H bond polar or nonpolar? Explain.
Both atoms are hydrogen (identical). Electronegativity: H = 2.1, so ΔEN = 0. Electrons shared equally → nonpolar bond.
Is the H–Cl bond polar or nonpolar? Calculate ΔEN.
H: 2.1, Cl: 3.0 ΔEN = 3.0 − 2.1 = 0.9 ΔEN > 0.5 → polar covalent bond. Cl pulls electrons → δ⁻ on Cl, δ⁺ on H.
Would C–C or C–O be more polar?
C–C: ΔEN = 0 (identical atoms) → nonpolar. C–O: C = 2.5, O = 3.5 → ΔEN = 1.0 → polar. C–O is more polar because oxygen is much more electronegative.
Flashcards
Quick quiz
Q1.The H–H bond is…
Q2.Which bond is most polar?
Q3.In a polar covalent bond, the more electronegative atom is…
Q4.Electronegativity difference > 1.7 suggests…
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Common mistakes
All covalent bonds are the same. — Correct: Covalent bonds range from nonpolar (equal sharing) to polar (unequal sharing).
Polar bonds have integer charges like +1 or −1. — Correct: Polar bonds have partial charges (δ⁺, δ⁻), not full integer charges.
A nonpolar bond means no electrons are shared. — Correct: Nonpolar bonds share electrons equally; electrons are still present.
Only nitrogen and oxygen can make polar bonds. — Correct: Any two atoms with different electronegativities make a polar bond.
FAQ
What determines if a covalent bond is polar or nonpolar?
The difference in electronegativity (ΔEN) between the two atoms. ΔEN ≈ 0 → nonpolar; ΔEN > 0.4 → polar.
Is water's O–H bond polar?
Yes, highly polar. Oxygen (3.5) is much more electronegative than hydrogen (2.1), ΔEN = 1.4.
Why is Cl–Cl nonpolar?
Both atoms are identical chlorine, so they have the same electronegativity. Electrons are shared equally.
Can a molecule have polar bonds but be nonpolar overall?
Yes — if polar bonds are arranged symmetrically, their dipoles cancel (e.g., CO₂).