Properties of Water (AP Biology)

Vocabulary flashcards covering the key concepts about water’s polarity, hydrogen bonding, and how these properties enable cohesion, adhesion, solvent abilities, and temperature regulation.

Polarity

The uneven distribution of electrical charge within a molecule, giving partial positive and negative ends; in water, this polarity enables hydrogen bonding.

Hydrogen bond

A weak attraction between a hydrogen atom bound to an electronegative atom (like O) and another electronegative atom in a nearby molecule, crucial for water’s properties.

Water polarity

Water’s polarity as a polar molecule with partial charges on its atoms, allowing it to interact with other polar/charged substances.

Cohesion

Attraction between water molecules via hydrogen bonds, causing water to stick together.

Adhesion

Attraction between water molecules and other surfaces, causing water to cling to containers or plant cell walls.

Surface tension

Tension at the surface of a liquid caused by cohesive forces; water’s surface behaves as if coated with a tight skin.

Capillary action

The movement of water up narrow tubes or porous materials due to the combined effects of cohesion and adhesion.

Solvent

A substance (like water) that dissolves other substances; water is an excellent solvent because of its polarity.

Heat of vaporization

The energy required to convert liquid water into gas, largely due to breaking hydrogen bonds.

Expansion on freezing

Water expands when it freezes due to the hydrogen-bond–driven open lattice structure.

Ice is less dense than water

Ice floats on liquid water because its solid form is less dense, due to the open hydrogen-bonded structure.