Subject: Why don't chlorine gas bubbles rise when salt dissolves?

I understand that when salt dissolves in water the sodium and chlorine ions 
are broken by the charge of the water molecules and are surrounded by a shell 
of water molecules. However, I don't understand how the salt can retain its 
physical properties once the bonds are broken and the elements themselves are 
separated. I know that on its own, chlorine is a poisonous green gas, and 
sodium is a highly reactive silvery metal.  If the bonds are being broken, how 
is this a physical change?  I did a lab with my students in which we broke 
water into its elements by sending an electric current through the water.  The 
result was bubbles of oxygen and hydrogen rising to the surface.  How come it 
is different when the sodium chloride is broken?  Does it have to do with the 
hydration?  
 I am a middle school science teacher in an international school in Jakarta.  
I have been teaching my students about solubility and have been driving myself 
crazy with this question, the answer to which is sure to be maddeningly 
simple.  

Re: Why don't chlorine gas bubbles rise when salt dissolves?