Water and Cool Stuff Ubiquitous in Nature Hydrogen Bonding Adhesion – Cohesion Capillary Action Surface Tension

Why is water so important? All living things need water. Approx 70% of the Earth is covered by water. Approx 70% of our bodies are made of water. Water exists in all 3 states of matter on Earth. Water is the ‘universal solvent’. Water can act as either an acid or a base. Water expands as it freezes. Water forms hydrogen bonds making cohesion and surface tension possible. Water has a high specific heat. (Is a heat sink)

Hydrogen Bonding An attraction between hydrogen and the relatively positive end of a polar molecule.

Adhesion An attraction between different substances.

Cohesion An attraction between substances of the same type.

Surface Tension A phenomenon created by the force of cohesion Surface Tension A phenomenon created by the force of cohesion. (Especially water)

Capillary Action A phenomenon created by both adhesion and cohesion forces.

Questions to Ponder How is capillary action relevant to biology? Why is water a polar molecule? Why is there an uneven sharing of electrons in water? Why do electrons have an affinity for oxygen? What type of bond is between the oxygen and hydrogen? What is the difference between cohesion and surface tension? What types of bonds are found between water molecules? Why do premature babies often have trouble breathing?