This absorption happens when two atoms collide with each other while one of them has an excited electron.

In order to compress the spring in the first place, the atoms must collide with sufficient energy.

Conduction of heat typically occurs as molecules or atoms collide transferring the heat between each other.

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

In nuclear fusion, atoms collide inside a reactor at extremely high temperature and pressure, releasing energy that can be harnessed to produce electricity.

Usually when two atoms collide, they bounce off each other like billiard balls.

'One of 'em says that everything happens by pure chance, like atoms falling through space, colliding with each other occasionally and cannoning off to start new collisions.

When atoms collide, there are no smaller particles for their kinetic energy to partition into.

Everything that occurs is the result of the atoms colliding, rebounding, and becoming entangled with one another, with no purpose or plan behind their motions.

Bound-bound transitions occur when the ions and neutral atoms collide, transferring an electron from the atom to the ion.