How do you determine polarity?

• A. Use the chart of electronegativity values and compare the difference between the bonded atoms.
• B. Add the atomic numbers of the atoms.
• C. Count the total number of bonds in the molecule.
• D. Measure the compound's boiling point.

Answer: (A)

Polarity comes from uneven electron distribution in a bond. The best way to determine it is to compare the electronegativity values of the bonded atoms using a chart. The bigger the difference in electronegativity, the more the electrons are pulled toward the more electronegative atom, creating a dipole. If the difference is small, the bond is essentially nonpolar; a moderate difference gives a polar covalent bond; a large difference yields an ionic character. To decide the molecule’s overall polarity, also consider geometry: polar bonds can cancel in a highly symmetric molecule, making the molecule nonpolar, or they add up to give a polar molecule if the geometry prevents cancellation. By looking up electronegativity values and calculating the differences, you can classify each bond and then assess whether the molecule is polar.