The Composition of Water

H2O

104.5°

Because oxygen withdraws the shared electrons closer, resulting in an unequal distribution of electrons.

The important properties of water discussed in the text are cohesion, heat capacity, density, and its role as a universal solvent.

Cohesion refers to the mutual attraction of like molecules. In water, cohesion is caused by the ability of water molecules to form hydrogen bonds with each other. This cohesion gives water its surface tension, allows light objects to float on water, and contributes to water's high boiling point.

Water's high heat capacity means that it requires a large amount of energy to change its temperature. This helps regulate temperatures in coastal areas and allows marine organisms to survive in a specific temperature range. Water's high heat of evaporation allows it to cool the surrounding environment when it evaporates, making it important for temperature regulation and maintaining stable environments for organisms.

Water is considered a universal solvent because of its polarity. The polar nature of water allows it to attract and dissolve a wide range of substances, making it capable of dissolving more substances than any other solvent.

Water is amphoteric, meaning it can act as both an acid and a base. As an acid, it donates a proton and becomes a hydroxyl anion. As a base, it receives a proton and becomes a hydronium cation.

Water's unique properties, such as its ability to regulate temperature, support the water cycle, and exhibit cohesive behavior, make life on Earth and within biological organisms possible. Water plays a crucial role in maintaining the temperature of the human body, facilitating evaporative cooling and sweating. Additionally, water's cohesive nature allows it to travel from roots to leaves in plants through capillary action. Water also plays a key role in the water cycle, moving around the Earth and atmosphere in different phases.

Ice floats on water because it is less dense than liquid water. When water freezes, its molecules form a crystal lattice structure with more space between them, causing the ice to be less dense. This lower density allows ice to float on the denser liquid water.