Bond polarity and dipoles
Polar bonds do not always make a polar molecule. The shape decides.
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- Bond dipole
- Net dipole
A flat view of a three-dimensional molecule, turned slightly off-axis so bonds behind the page can still be seen. Where arrows overlap, the net arrow is the answer.
Description of this simulation
CO2 is linear, with 2 bonds to C. 2 of them are polar, the largest difference being 0.89. The bond dipoles point in directions that cancel exactly, so the molecule as a whole has no dipole. Polar bonds, non-polar molecule — the shape decides.
A non-polar molecule
Polar bonds, non-polar molecule. The bond dipoles point in directions that cancel exactly, so the molecule as a whole has none.
- Net dipole
- Cancels to nothing
- Polar bonds
- 2 / 2
A relative magnitude in electronegativity-difference units, not a dipole moment in debye — no dipole moment has been measured here.
Bond by bond
- C–OΔχ 0.89Polar covalent
- C–OΔχ 0.89Polar covalent
A conventional reading, not a law: below 0.4 counts as non-polar, above 1.7 as largely ionic. Real bonds sit on a continuum.
Where this came from
The bonds are the ones the Lewis builder drew and the shape is the one the geometry lab derived, from the same numbers. All three labs describe one molecule.
What this model shows — and what it simplifies
Educational ModelBond dipoles are summed as vectors along the real three-dimensional bond directions, using Pauling electronegativity differences.
Where do we see this in real life?
This is why oil and water do not mix, why a microwave heats food by shaking water molecules and not the plate, and why carbon dioxide is a gas you can breathe out while water is a liquid you are mostly made of.