A shared pair can spend more time near one atom. That end becomes partially negative and the other partially positive. Partial charges describe uneven sharing, not complete electron transfer.

The model has a domain of validity. Explain its assumptions before using it in a changed context, then compare your prediction with evidence.

• Electronegativity is an atom’s pull on shared bonding electrons. Unequal pull makes a polar bond.
• A polar bond does not by itself prove a whole molecule is polar; shape determines cancellation.