Why HF is more polar between HF and H2O?
Why HF is more polar between HF and H2O?
HF is more polar than H2O because fluorine is more electronegative than oxygen. Electronegativity is a measure of how strongly an atom attracts electrons. In the HF molecule, the fluorine atom pulls the shared electrons in the H-F bond more strongly toward itself than the hydrogen atom does. This creates a partial negative charge on the fluorine atom and a partial positive charge on the hydrogen atom. The opposite ends of the molecule are therefore attracted to each other, creating a dipole moment.
In the H2O molecule, the oxygen atom is also more electronegative than the hydrogen atoms. However, the difference in electronegativity between oxygen and hydrogen is not as great as the difference in electronegativity between fluorine and hydrogen. Therefore, the dipole moment in the H2O molecule is not as strong as the dipole moment in the HF molecule.
In addition to the difference in electronegativity, the shape of the molecules also plays a role in their polarity. The HF molecule is linear, so the dipole moment is concentrated along the axis of the molecule. The H2O molecule is bent, so the dipole moment is spread out over a larger area. This makes the dipole moment in the HF molecule stronger than the dipole moment in the H2O molecule.
