What is the most explosive reaction you can get with just two elements and what are those elements?

Question: What is the most explosive reaction you can get with just two elements and what are those elements?
- Keywords:
  chemical,
  explosion,
  reaction
Asked by the josh to Chris, Josh, Rebecca, Rob, Susan on 19 Jun 2015.
- Susan Cartwright answered on 19 Jun 2015:
  
  I’m not a chemist, but probably caesium and fluorine, since they are the most reactive of the alkali metals and the most reactive of the halogens respectively. They combine to form caesium fluoride, with a *lot* of energy released.
  (Caesium and water is also spectacularly explosive, but water’s not an element.)

Question: What is the most explosive reaction you can get with just two elements and what are those elements?