WATER

Our planet would better be called Water Earth after all is 70% covered in water at an average depth of 3km although most abundant life occurs in the shallows.
All life forms are at least 65% H2O and life originated and evolved most important characteristics in water.

The most important characteristic of water is its electrostatic polarity. Most of its characteristics and unique qualities stem from its polar nature.

      Characteristics and important qualities in regard to life on Earth

1) water is a universal solvent , can form weak bonds with with other polar molecules and can break (ionize)
- polar molecules are called hydrophobic
- apolar molecules are called hydrophobic
- molecules that have a polar and nonpolar sections are called amphipathic

2) Water organizes molecules leading to such things as oil droplets and cell  membranes ...... in a tendency to minimize system energy levels

Hydrogen Bonding	Micelle Formation
Self Organization of cell membranes	Trans membranal protein

3) surface tension allows insects to skate across the surface of water , bird feathers can repel water
- problem is created in lungs and is solved by surfactants
- surfactants are not produced until late term in pregnancy premies suffer without surfactant

Alveoli are the gas exchange site of the lungs and must be moist to allow for effect diffusion	Surfactants are amphipathic! They disrupt the Hydrogen bonds between water molecules

4) Energy is required for change of state
- evaporation of water keeps the planet and our bodies cool
- water droplets protect leaves from frost damage (to a point)
- ocean currents circulate vast quantities of solar energy throughout the globe

5) Ice floats
water is the only substance that is most dense at temperatures above its freezing point
- warm water is kept under ice

6) adhesion - water will rise in a narrow tube by capillary action
- water will flow up the xylem tubes of plant vascular tissue
 

Capillary action	Meniscus	Water is drawn up xylem tubes in plants

7) Acid formation - water is an acid and a base and is suitable environment for acid formation
- acids form when protons (hydrogen ions ) are donated to solution
8) crystal formation - water can precipitate as snow flakes that insulate hibernating plants and animals
- snow increases the albedo (reflectivity) of Earth's surface
9) isotopes -  tritium and deuterium used in reactors and research