Re: Phase change from gas to plasma

The transition from a gas to a plasma is called ionization.  There is some 
disagreement on whether or not the transition from a gas to a plasma is a 
true phase change.  The answer depends on how you define a phase change.

Some feel that there are only three states of matter: solids, liquids, and 
gases.  They hold that plasma is not a new state of matter, but rather is 
an ionized gas.  Thus, in this view, plasma is just a special case of the 
gas phase.