It is assumed that unless atoms or molecules collide with enough energy to form the transition structure, then the reaction does not occur.

These molecules collide with one another and with the dispersed particles.

A chemical reaction takes place only when the reacting molecules collide.

Yet, we are forcing the pressure to remain fixed, which must mean that the molecules are not colliding with the walls as often.

For bimolecular reactions, two molecules collide and react with each other.

The second molecule, B, collides with the surface, forming a mobile precursor state.

Thus the molecules and atoms which make up the human body are vibrating, colliding, and moving.

Bradburn This is because the molecules are moving faster at a higher temperature, and collide with each other more often.

The frequency with which the molecules or ions collide depends upon their concentrations.

At high pressures molecules are colliding more often.