The answer is: Electrons are shared in each pi bond. If the pi bonds flip back and forth between the adjacent p-orbitals on the two sides of an atom, the shared electrons in the p-orbitals can become delocalized.
Hope this help
        
             
        
        
        
I believe the answer you are looking for is Static Friction. Static Friction is the force that holds an object in place until it starts to move. Then it switches to rolling friction. 
For example, if you have a 1/2 ton truck sitting in front of you and the truck is in neutral. (meaning it can roll if pushed). The truck is extremely hard to move at first. That is because static friction is holding it in place until the amount of force exceeds the limit of static friction. 
So if we continue to push at the truck and you feel it starting to move, then once it starts moving it is much easier to push, that is because we moved past static friction to rolling friction. Rolling friction is what helps slow things down. If you roll a ball across a carpet floor it eventually comes to a stop. 
 
        
                    
             
        
        
        
Temperature. Water is an example. When water is at room temp. its liquid. When water is at boiling temp. It is a gas. And when water is at freezing temp. Its a solid.
        
                    
             
        
        
        
Solubility and temperatures are directly related. The higher the temperature of the solvent, the higher the solubility of the solute in the solvent.
Dissolving a solute in a solvent is an endothermic process hence providing heat favors the  process. Higher temperatures cause the molecules of the solvent to have high kinetic energy hence bombard each other and with that of the solute with high frequency. This then ensures fast diffusion of the solute particles in the solvent.