Water covers more than 75% of the surface of the Earth. While much of it is in the oceans, lakes and rivers on the continents contain a lot of water as well. Water is also the most abundant molecule in just about every organism on Earth.

It's easy to take water for granted, but life changes drastically when water is either scarce or plentiful. Droughts and floods can destroy crops and lead to food shortages. Within our body, too little water can lead to death, and too much fluid in the lungs or heart can be fatal.

In order to appreciate the factors that lead to the scarcity or abundance of water in an environment or in an organism, we need to understand the molecular structure of water. Water's structure has important implications for its chemical and physical properties, and we'll explore these in detail in this Lesson.

Did you ever wonder why a water droplet is spherical, and not some other shape? Or why table salt dissolves in water, but cooking oil doesn't? These properties of water are directly related to its chemical nature. As we learn about some of the unique properties that make water an ideal solvent for biological systems, we'll be focusing on the important relationship between its structure and function.

Objectives

• to understand the properties and chemical structure of water
• to understand what gives water cohesion, and adhesion.
• to understand how water is the best solvent