Polar Covalent Bond
A covalent bond in which the shared electrons are unequally distributed because the bonded atoms differ in electronegativity.
Formula / equation
δ⁺A—Bδ⁻
Unit
D
In depth
The more electronegative atom acquires a partial negative charge and the other a partial positive charge, creating a bond dipole. Whether the whole molecule is polar depends on whether these bond dipoles cancel by symmetry, which is why CO₂ is non-polar despite having two strongly polar bonds.
Examples in the real world
H–Cl with a dipole moment of 1.08 D; the O–H bonds in water, which do not cancel because the molecule is bent.