BIOLOGY : CHAPTER 1

                          MOLECULES OF LIFE                                   

                 

1.1-WATER                                                                                                                    

 How water does looks likes??

Water consist of one oxygen atom and two hydrogen atoms.Polar covalent bonds join between two hydrogen atoms and one oxygen atom.Hydrogen atoms is partially positive charges and oxygen atom is partially negative charge.This known as dipole.

                                             

                                           

Water forms in 'V' shape not a straight line.Oxygen is more electronegative than hydrogen.It's two covalent bonds spread apart at an angle of 104.5 degrees..

               PROPERTIES OF WATER AND ITS IMPORTANT

1-WATER IS POLAR MOLECULES.

Water can acts as universal solvent for polar molecules such as sugar and salt.

How salt dissolves in water??

Salt is NACL.NACL is dissolves after water molecules surround the ion and keep them dispersed include.Each sodium ion attract negative end charges oxygen while  at the same time chlorine ion is attract to positive charge end of hydrogen ion in molecules of water.water surround the ions and keep them separate include by formated of hydration shell.

2-WATER HAS HIGH SPECIFIC HEAT OF CAPACITY

 The heat capacity of water is the amount of heat must be absorb or release to increase the temperature.Water has high specific heat capacity mean that a larges amount of heat need to slight increase the temperature.So, water temperature does not increase as fast as other substances.

So, water it important in allow ocean to maintain relatively constant temperature.

3- WATER HAS LOW VISCOCITY

Water can acts as lubricant for helps to minimize friction

4-WATER HAS HIGH LATENT HEAT OF VAPORIZATION

Latent heat of vaporization is a quantity of heat must be absorb to vaporize liquid to gas.


5-WATER HAS HIGH SURFACE TENSION
In the body of water, water molecules within are attracted equally by cohesion.At the air-water interface,cohesive force only from interior.The unequal attraction cause high surface tension at the surface of water.It allow small organism to walk on the water without breaking the surface.








6-WATER HAS MAXIMUM  DENSITY AT 4 DEGREE CALCIUS
Water achieves its maximum density at 4 degree calcius.Therefore,ice is less than water and float on top of water.water can acts as insulator to insulate the layers bellow from further cooling and freezing.This allowing the aquatic organism to survive.