Here's why:
* Oxygen is more electronegative than hydrogen: Oxygen has a stronger pull on electrons than hydrogen. This means the shared electrons in the O-H bonds spend more time closer to the oxygen atom.
* Bent molecular geometry: The water molecule has a bent shape due to the two lone pairs of electrons on the oxygen atom. This bent shape further concentrates the negative charge around the oxygen.
As a result, the oxygen atom in water carries a partial negative charge (δ-), while the hydrogen atoms carry a partial positive charge (δ+). This creates a polar molecule with a dipole moment.
