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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Bond dipole

The separation of charge within one polar bond, drawn as an arrow pointing toward the δ−\delta^- (more electronegative) atom, with a cross at the δ+\delta^+ tail. Its size grows with ΔEN\Delta\text{EN}.

Bond dipole in H–FIn H–F the shared electrons sit closer to fluorine (electronegativity 4.0) than hydrogen (2.1). H carries a partial positive charge, F a partial negative charge, and the dipole arrow points from H toward F.HFδ+δ−dipole arrow points to the more electronegative atomEN 2.1EN 4.0

H–F: the arrow points from δ+\delta^+ H to δ−\delta^- F.

Example

Each C=O in COX2\ce{CO2} has a sizeable bond dipole (ΔEN=0.89\Delta\text{EN} = 0.89), but the two point in opposite directions and cancel.

See alsoDipole momentPolar covalent bondPartial charge (δ+ / δ−)Polar molecule