[Jules18]

I was taught in high school that all reactions are governed by the valence electrons.  of the atoms involved.

Then I was taught that the term "redox reaction" applied only to rxns where e- were exchanged, or oxidation numbers were changed.

But the first fact would lead me to believe that all rxns had to be redox. 

Can anyone think of any rxns that aren't redox?  Why else would rxns occur if the electron configurations didn't get to become more stable?

~Jules~

[lancenti]

AgNO₃ (aq) + NaCl (aq) AgCl (s) + NaNO₃

All ions there retain their original oxidation state, but a precipitation reaction occurs.

Reactions occur not only because electron configurations become stable. In Physical Chemistry, you'll learn of things such as Gibbs Free Energy, Enthalpy and Entropy which tell you whether or not a reaction is Energetically Feasible or Spontaneous.