What happens to colloidal particles in a liquid medium? And how to stabilize it?
"Colloidal particles: What are colloidal systems, give an example,--"


  Milk, bear foam, paste, blood, ---


"what happens to colloidal particles in a liquid medium."


  I understand the q as solid in liquid so a gel. Examples about gel are "agar, gelatin, jelly and opal" according to my lecture slides. The electrostatic forces are in some sort of middle phase: not enough to repulse into liquid form but not strong enough to form liquid either.


"How to stabilize colloidal systems in a liquid medium."


  Wikipedia about stability (here)
  
  
    "The stability of a colloidal system is the capability of the system
    to remain as it is. Stability is hindered by aggregation and by
    sedimentation phenomena, that determine phase separation."
  
  
  Now different things to consider are:
  
  
  Electrostatic stabilization
  
  
  
    "In a stable colloid, mass of a dispersed phase is so low that its buoyancy or kinetic energy is too weak to overcome the electrostatic
    repulsion between charged layers of the dispersing phase."
  
  
  
  steric stabilization 
  
  
  
    "particles in polymers which prevents the particle to get close in the range of attractive forces."