electrostatic surface

WATER & SOLUBILITIES

POLARITY

Since Oxygen has a greater electronegativity than Hydrogen it pulls the shared electrons towards itself. This causes the oxygen to become slightly negative and the hydrogens to become slightly positive. The polar water molecules attract each other and exclude neutral non-polar molecules in what is called the hydrophobic effect. 



movie of disolving salt (uakron animation)

Liquid Water

Ice

movie of water
Polar liquids such as water will disolve other polar molecules, simiarly non-polar liquids tend to disolve in each other. Simply put "Like disolves Like"

 

What if a large molecule has parts that are polar and parts which are non-polar? (A lipid for example)
When in water the molecules will arrange themselves in structures such as micelles or membranes, in which the polar parts stick out into the water and the non-polar parts are sequestered away from the water
micelles
membranes
oil micelle and soap