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Solvent action of water (H₂O)

• Water (H₂O) molecules are made up of two (2) hydrogen (H) molecules and one oxygen (O) molecule arranged as shown in the fig. 8.
  
  
• Oxygen (O) is an element that likes to draw negatively (-ve) charged electrons from its nearest neighbours closer to itself (from hydrogen in this case).
  
  This leaves the hydrogen (H) atoms slightly +ve (positively) charged (see fig. 8).
  
  With the opposite ends of the H₂O (water) molecules, being charged oppositely makes H₂O a polar molecule. A simple fact that has many and far reaching implications.
  
  One such implication is hydrogen bonding between the water molecules giving rise to water's surface tension, boiling and melting points, density of ice and water's viscosity.
  
  
• When charged molecules are introduced into H₂O, the oppositely charged ends of water seperate, line up and surround such molecules as shown in fig. 9.
  
  When ionic compounds are introduced to H₂O, the attraction of water's charged ends over comes the attractions between the atoms of the ionic compound and their reformation is restricted due to the hydration shells formed by the H₂O molecules as shown in fig. 9
  
  This is how water acts as a solvent
  
  When the amount of ionic compound exceeds the number of H₂O molecules able to surround them, the solution is said to be supersaturated.
  
  
• A supersaturated solution will usually show a solid precipitate (deposit) of the excess compound in solution.