•A molecule that is moving has
 kinetic energy;
 faster the motion, the greater the KE. When molecules collide some of the KE is changed into vibrational
 energy of the bonds . Sometimes there is enough energy gained through collision to break a
 bond and
 initiate reaction. If the energy is not enough to break the bond, the molecules bounce of one another with no
 reaction occurring.
 •So there is some minimum collision energy below which no
 reaction occurs.