Bond Polarity
The degree of unequal electron sharing in a covalent bond, arising from an electronegativity difference between the bonded atoms.
Formula / equation
Δχ = |χ_A − χ_B|
Unit
Dimensionless
In depth
Polarity increases smoothly with electronegativity difference, so there is no sharp line between covalent and ionic bonding — only a continuum. Polar bonds create reactive sites, since the partially positive atom attracts nucleophiles and the partially negative atom attracts electrophiles.
Examples in the real world
C–F is strongly polar (Δχ = 1.43); C–H is nearly non-polar (Δχ = 0.35), which is why alkanes are unreactive.