Calculate molecular dipole moments and predict bond polarity from electronegativity
1 pm = 10⁻¹² m
Dipole Moment (μ): A measure of bond polarity. It's a vector quantity pointing from positive to negative charge (δ⁺ → δ⁻). Units: Debye (D) or C·m.
Electronegativity Difference (ΔEN): Larger ΔEN means more polar bond. ΔEN > 1.7 typically indicates ionic character. Pauling scale is most common.
Molecular Polarity: Even with polar bonds, symmetric molecules (CO₂, CCl₄) have μ = 0 due to vector cancellation. Asymmetric molecules (H₂O, NH₃) have net dipole moments.
Applications: Dipole moments affect boiling points, solubility, intermolecular forces, and spectroscopy (microwave, IR). Polar molecules dissolve in polar solvents ("like dissolves like").
Dipole moments quantify the separation of positive and negative charge in polar bonds and molecules. Understanding dipole moments is essential for predicting intermolecular forces, solubility, and spectroscopic properties.