Polar bonds and whole-molecule dipoles

4 minAS Level3.6.2

AI-drafted, independently checked · not yet teacher-reviewed

By the end of this lesson

By the end, you can use electronegativity to explain bond polarity and decide whether a molecule has an overall dipole.

Who pulls the shared pair harder?

Electronegativity is an atom's ability to attract the shared pair of electrons in a covalent bond. If one atom attracts the pair more strongly, the electrons spend more time nearer it.

That end becomes slightly negative, written δ−; the other end becomes slightly positive, written δ+. The bond is polar.

Worked example: Compare two molecules

Decide whether CO₂ and H₂O have an overall molecular dipole.

Have a go first?

Dipole arrows point toward the more electronegative, slightly negative end.

Bond or molecule?

Fill in the blanksQuestion 1 · Recall

The atom that attracts a shared pair more strongly has a electronegativity and becomes slightly .

Multiple choiceQuestion 2 · Apply

Each C=O bond in CO₂ is polar. Why does straight CO₂ have no overall molecular dipole?

AIts equal bond dipoles point in opposite directions and cancel.BIts C=O bonds are not polar after all.CIts atoms have no electrons to share.DThe molecule is charged overall.

Answer the 2 questions above to continue.

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