What role does the oxygen atom play in water's polarity?

The role of the oxygen atom in water's polarity is crucial due to its electronegativity. In a water molecule (H₂O), oxygen is more electronegative than hydrogen, meaning it has a stronger tendency to attract electrons towards itself. This results in the oxygen atom carrying a partial negative charge because the shared electrons are drawn closer to oxygen, creating an uneven distribution of electron density. Consequently, this polarity is responsible for many of water's unique properties, such as its solvent capabilities and high surface tension.

While hydrogen atoms develop partial positive charges as a result of this unequal sharing of electrons, the fact that oxygen pulls electrons more strongly (demonstrating its electronegativity) explains the overall molecular polarity of water. This characteristic is central to how water interacts with various solutes, making it a versatile solvent in biological systems.