A polar covalent bond is a covalent bond in which the shared electron pair is pulled closer to one atom than the other, creating a slight charge separation (dipole) across the bond.

Quick Scoop

1. Core idea

  • In a polar covalent bond, electrons are shared , but not equally.
  • The atom that attracts electrons more strongly becomes slightly negative (δ−), and the other becomes slightly positive (δ+).
  • This uneven sharing is caused by a difference in electronegativity between the bonded atoms.

2. How it sits between ionic and covalent

  • Pure covalent bond: electrons are shared equally (like in H₂, Cl₂), so there is no permanent charge separation.
  • Ionic bond: one atom essentially takes an electron from the other, forming full charges (e.g., Na⁺ and Cl⁝ in NaCl).
  • Polar covalent bond: sits between these extremes—electrons are still shared, but one side “owns” more of the electron density.

3. Role of electronegativity

  • Electronegativity measures how strongly an atom attracts shared electrons.
  • A bond becomes polar covalent when the difference in electronegativity is moderate—not zero (nonpolar) and not huge (ionic).
  • A commonly used rough range for a polar covalent bond is an electronegativity difference of about 0.4 to 1.7 between the two atoms.

4. Dipole and bond polarity

  • Because one end is δ+ and the other is δ−, a polar covalent bond has a bond dipole moment , often drawn as an arrow pointing toward the more electronegative atom.
  • The magnitude of this dipole depends on how big the electronegativity difference is and the distance between the atoms.

5. Everyday examples

  • H–Cl: hydrogen–chlorine bond is polar covalent; chlorine is more electronegative and carries δ−, hydrogen carries δ+.
  • O–H in water (H₂O): oxygen attracts electrons more strongly than hydrogen, making each O–H bond polar covalent.
  • Many bonds in organic and biological molecules (like C–O, N–H) are polar covalent and control solubility, reactivity, and intermolecular forces.

6. Why polar covalent bonds matter

  • Polar covalent bonds create polar molecules when their dipoles do not cancel out (as in H₂O), giving molecules partial positive and negative regions.
  • These partial charges drive hydrogen bonding, higher boiling points, and interactions like “like dissolves like” (polar substances dissolve in polar solvents such as water).

7. Tiny story to remember it

Imagine two friends sharing a blanket on a cold night.

  • If they hold it exactly in the middle, that’s like a nonpolar covalent bond.
  • If one yanks the blanket completely away, that’s like an ionic bond.
  • If one tugs it a bit closer but still shares, that’s like a polar covalent bond : both still share, but one clearly has more. This “blanket imbalance” is your mental picture of bond polarity.

Information gathered from public forums or data available on the internet and portrayed here.