Water is polar; shape is bent (approx. V); the highly electronegative oxygen pulls electron density toward itself, giving \delta^- on O and \delta^+ on each H.
Water covers \tfrac{3}{4} of Earth's surface.
Hydrogen Bonding
Hydrogen bonds form between a hydrogen atom on one water molecule (partly positive) and the oxygen on a neighboring molecule (partly negative).
Cohesion and Adhesion
Cohesion: water molecules stick to each other via hydrogen bonds.
Adhesion: water sticks to surfaces (e.g., xylem walls in plants).
Surface Tension
Cohesion contributes to surface tension; enables phenomena like water striders.
Plant Water Transport (Xylem)
Water transport occurs in xylem vessels; adhesion to walls + cohesion between molecules help resist gravity.
Evaporation from leaves (transpiration) pulls up the rest of the water chain.
Biological Significance
Water's unique properties support biology and life.