Characteristic Properties of Water

     72% of earth is water, and living cells contain 70 - 80% water.  Obviously, it is a very important substance, and it has many unique, unusual, and amazing properties.

Polarity:
     Water is a polar covalent bond between one oxygen atom and two hydrogen atoms.  This means two hydrogen atoms decided to share their one electron each with an oxygen atom.  Since oxygen atoms are bigger, they pull the shared electrons (electrons = negative charge) closer to their nucleus, which contains neutrons as well as protons that have a positive charge. This makes the electron and negative charge farther away from its Hydrogen nucleus.  Because of this, the side of the water molecule with the hydrogen atoms has a slight positive charge, and the opposite side has a negative charge.

Solubility:  

     Because water has both a negative and a positive charge,  negatively and positively charged atoms are attracted to it and therefore many different things can dissolve in water, for example, sugar, ions, Na

+

.  This is why water is known as the universal solvent.  

Adhesion and Cohesion:
     Water sticks together, and that is why it forms droplets and puddles.  The negative side of a water molecule is attracted to the positive side of another molecule, and they stick together this way.  It is called a Hydrogen bond.

Density:
     The density water is 1g/ml.  Water in its solid form is less dense than water in its liquid for and therefore, it floats.  For example, icebergs float on the top of the ocean.  The reason why ice is less dense then water is because of the hydrogen bond is stronger, and the molecules are more dense and less stable in water in its liquid form.  The molecules in frozen water form a lattice formation, it is more stable and less dense, and therefore ice is lighter per ml than water.


Specific Heat:
     Specific Heat is the amount of energy necessary to raise one gram of a substance one degree celsius.  Water has a high specific heat because the molecules are bound together so tightly that it takes more energy to break them apart.  For example, when you boil water on a stove, it takes a while for the water to heat up, however the pot or thing that you are using to boil the water in gets hot very quickly.  This indicates that water takes a long time to heat up, and also it takes a long time to cool down.


Neutral pH:
     H₂O is constantly ionizing.  This means the water molecules are separating, creating ions OH^- and H⁺.   As they separate, the water molecules combine again, to form H₂O.  Because there is an equal amount of H⁺ and OH^- molecules in water, water is neither acidic or basic.  Therefore pure water is neutral and has a pH of 7.