Bond Polarity, Dipole Moment, and Percent Ionic Character

The type of chemical bonds, whether it is nonpolar covalent, polar covalent, or ionic, is largely determined by the difference in the electronegativity between the bonding atoms and their bond length.

In bromine, the bond between the two bromine atoms is nonpolar since the difference in electronegativity between them is zero.

In hydrogen bromide, the bond is polar covalent since the more electronegative bromine attracts the electron density away from the less electronegative hydrogen atom.

In potassium bromide, the bond is an ionic bond due to the larger difference in electronegativity, resulting in complete electron transfer from potassium to bromide.

When two equally, but oppositely charged particles are separated by a distance a dipole, is formed. The quantitative measure of the dipole is called the dipole moment represented by the letter µ, which is the product of the magnitude of the charges, Q, reported in coulombs, and the distance between the charges, r, reported in meters.

The dipole moment is given in debye units, where one debye equals 3.34 × 10⁻³⁰ C·m.

Whether a compound is polar covalent or ionic can be determined by calculating the percent ionic character, which is th