A polar molecule has an uneven distribution of electron density that produces a net molecular dipole. A nonpolar molecule has no lasting net dipole, either because its bonds are only weakly polar or because its bond dipoles cancel through symmetry.
Bond polarity alone is not enough to classify a whole molecule. Carbon dioxide has polar C=O bonds but is linear and symmetric, so their dipoles cancel. Water has polar O–H bonds and a bent geometry, so its dipoles reinforce one another.
How to identify molecular polarity
First identify polar bonds from electronegativity differences, then determine the molecular geometry and ask whether the bond dipoles cancel. Lone pairs often change geometry: ammonia is trigonal pyramidal and polar, while boron trifluoride is trigonal planar and nonpolar despite its polar B–F bonds.
For larger organic molecules, functional groups and molecular shape both matter. Hydroxyl, carbonyl, amide, and charged groups usually increase polarity, while a large hydrocarbon region can dominate the behavior of an otherwise polar functional group.
Polarity, solubility, and intermolecular forces
“Like dissolves like” is a useful first approximation: polar solvents tend to dissolve polar or ionic solutes, and nonpolar solvents tend to dissolve nonpolar solutes. It is not an absolute rule because hydrogen bonding, ionization, temperature, and the relative sizes of polar and nonpolar regions also influence solubility.
How this dataset was assembled
Small inorganic examples are manually classified from molecular geometry and bond polarity. Organic examples use functional groups, hydrogen bonding, TPSA, and LogP as supporting evidence; borderline cases keep explicit notes.
Each row retains source identifiers where available. Molecular weight is calculated from the recorded formula, and the original names, structures, classifications, and database links remain visible so individual entries can be checked before reuse.
People also ask
How do you identify polar and nonpolar molecules?
Draw or determine the molecular geometry, mark the polar bonds, and add their dipoles as vectors. A nonzero result indicates a polar molecule; complete cancellation indicates a nonpolar molecule.
Why is water polar but carbon dioxide nonpolar?
Water is bent, so its O–H bond dipoles do not cancel. Carbon dioxide is linear, so its two equal C=O bond dipoles point in opposite directions and cancel.
Can a molecule have polar bonds and still be nonpolar?
Yes. Symmetric molecules such as CO₂, BF₃, CCl₄, and SF₆ have polar bonds whose dipoles cancel across the complete geometry.
Are all hydrocarbons nonpolar?
Most simple hydrocarbons are treated as nonpolar because C–C bonds are nonpolar and C–H bonds are only weakly polar. Substitution with heteroatoms or charged groups can make an organic molecule polar.
Sources and further reading
PubChem — Canonical compound identifiers, names, formulas, structures, SMILES, and downloadable compound records.
ChEBI — Chemical ontology classes, biological roles, synonyms, formulas, SMILES, InChI, and ChEBI identifiers.
RDKit — Derived descriptors such as molecular weight, LogP, TPSA, hydrogen-bond counts, and canonicalized structures.
OpenStax Chemistry — Chemistry definitions used for educational polarity, bonding, organic chemistry, and molecule-class explanations.