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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Partial charge (δ+ / δ−)

A fraction of an electron's charge that builds up on an atom in a polar bond: δ−\delta^- on the more electronegative atom, δ+\delta^+ on the other. A larger ΔEN\Delta\text{EN} means larger partial charges.

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

In H–F, F is δ−\delta^- and H is δ+\delta^+.

Example

In water, each H is δ+\delta^+ and the O is δ−\delta^-. Formal charges (00 on every atom of HX2O\ce{H2O}) do not show this.

See alsoPolar covalent bondBond dipoleElectronegativityFormal charge