Bond polarity
When bonded atoms do not attract electrons equally, electron density shifts. The bond becomes polarized: one end carries more negative character and the other more positive character.
The essential idea
When bonded atoms do not attract electrons equally, electron density shifts. The bond becomes polarized: one end carries more negative character and the other more positive character.
Example
In H–Cl, chlorine attracts electron density more strongly than hydrogen. The bond is polar without requiring a complete electron transfer.
Mini problem
Why is H₂ nonpolar?
Show the solution
Because the atoms are identical and attract electron density equally.
Common mistake
Do not replace reasoning with a memorized rule. Always check geometry, units, coefficients or model assumptions.
Guided exercise
Rank H–H, H–Cl and Na–Cl from least polarized to most polarized.
Show the detailed solution
H–H is nonpolar. H–Cl is polar. Na–Cl has much stronger ionic character. The ranking uses electronegativity difference and the chosen bonding model.
Avoid this
Caution: an electronegativity difference does not create a universal sharp boundary between 'covalent' and 'ionic'.