1. Oxygen is more electronegative: Oxygen has a higher electronegativity than hydrogen. This means it has a stronger pull on the shared electrons in the covalent bonds.
2. Electron distribution: As a result, the shared electrons spend more time closer to the oxygen atom, giving it a slightly negative charge (δ-).
3. Hydrogen becomes partially positive: The hydrogen atoms, having lost some electron density, become slightly positive (δ+).
4. Bent molecular shape: The water molecule has a bent shape, with the two hydrogen atoms at an angle of about 104.5 degrees. This shape further enhances the polarity by separating the positive and negative charges.
The combination of these factors creates a dipole moment in the water molecule, where one end is slightly negative and the other end is slightly positive. This polarity is responsible for many of water's unique properties, including:
* Strong hydrogen bonding: Water molecules attract each other through strong hydrogen bonds between the partially positive hydrogen atom of one molecule and the partially negative oxygen atom of another.
* High boiling point: The strong hydrogen bonds require significant energy to break, leading to water's relatively high boiling point.
* Excellent solvent: Water's polarity allows it to dissolve many ionic and polar substances.
* High surface tension: Water molecules at the surface experience a stronger attraction to each other than to the air molecules, creating a strong surface tension.
