Nucleation

• Nucleation starts the formation of crystals.Jupiterimages/Photos.com/Getty Images
  
  The name of the process that begins the growth of crystals is called nucleation. When the process of nucleation begins with the actual molecules themselves, then it is called unassisted nucleation. If, on the other hand, the nucleation process is started with the aid of solid matter that is already present inside of a solution, it is a process that is called assisted nucleation. It is important to note that the process of nucleation is a physical one rather than a chemical one.
  
  

Unassisted Nucleation

• Unassisted nucleation is one way that crystals can form.Jupiterimages/Photos.com/Getty Images
  
  Nucleation that is unassisted occurs when an attractive force exists between solute molecules in a solution. This usually occurs when the compound was solid when it was still pure. If these solute molecules are powerful enough to stay together so that two, three, fou, and then more molecules beyond that stay bonded, they will become a protocrystal. As the protocrystal continues floating in its solution, more solute molecules get attracted to it, and the crystal begins to grow further in this fashion.
  
  

Assisted Nucleation

• Crystals are also formed through assisted nucleation.Jupiterimages/Photos.com/Getty Images
  
  Nucleation that is assisted is quite similar to unassisted nucleation. As opposed to unassisted nucleation, nucleation that is assisted occurs on a surface that is a solid. For instance, a brick may act as the place where solute molecules are attracted to each other. Upon encountering the surface of the brick, solute molecules will absorb to the surface and then continue to aggregate on it. As they continue aggregating, a protocrystal starts to grow, and a crystal will form thereafter.
  
  

Best Conditions

• Too much heat discourages crystal formation.Jupiterimages/Photos.com/Getty Images
  
  The best conditions for crystal growth and formation are those that are near saturation and not too hot. Saturation is when a particular solution is incapable of dissolving more of a specific kind of substance. If more solute molecules are present in any solution, there will be a greater chance that said molecules will meet each other and bond. Heating up a solution is not advisable because that will create conditions where the aggregation of the molecules will tend to break apart. The heat in solutions that are too hot create a randomizing effect on the molecules, thus decreasing the likelihood of crystal formation.