How does electronegativity affect the sharing of electrons in a bond?

Electronegativity is defined as the ability of an atom to attract a shared pair of electrons toward itself when part of a chemical bond. It is the primary factor determining how electrons are distributed between bonded atoms.123

• Nonpolar Bonds: When atoms have approximately equal electronegativities, they share the electron pair equally, resulting in little to no charge separation.13
• Polar Bonds: When atoms have different electronegativities, the more electronegative atom pulls the shared electrons closer to itself. This creates an uneven distribution of charge, where the more electronegative atom acquires a partial negative charge and the other atom acquires a partial positive charge.34
• Ionic Bonds: As the difference in electronegativity increases, the dipolar character of the bond grows. When the difference is very large, the more electronegative atom effectively gains complete control over the electron pair, resulting in an ionic bond.34

Ultimately, bonding is viewed as a continuum ranging from purely covalent (equal sharing) to ionic (complete transfer), with the electronegativity difference dictating where a specific bond falls on this spectrum.34