Polar Bond
Definition
A covalent bond where electrons are shared unequally, giving one end a slight positive charge and the other a slight negative charge.
Symbol: ·
Technical definition
A polar covalent bond forms between atoms with significantly different electronegativities (typically 0.4 to 1.7 on the Pauling scale), creating partial charges and a bond dipole moment. It is intermediate between nonpolar covalent and ionic bonding.
Example
In hydrogen chloride (H-Cl), chlorine pulls the shared electrons closer, so the hydrogen end is slightly positive and the chlorine end slightly negative.
Common confusion
A molecule can have polar bonds but still be nonpolar overall. In CO2 the two polar C=O bonds point in opposite directions and their dipoles cancel.