The kinetic theory of matter helps us to explain why matter exists in different phases (i.e. solid, liquid and gas), and how matter can change from one phase to the next. The kinetic theory of matter also helps us to understand other properties of matter.

The kinetic molecular theory of matter states that: Matter is made up of particles that are constantly moving. All particles have energy, but the energy varies depending on the temperature the sample of matter is in. This in turn determines whether the substance exists in the solid, liquid, or gaseous state.

Assumptions. Molecules are in a state of continuous motion and hence they possess kinetic energy. The kinetic energy of molecules increases with an increase in temperature and decreases with a decrease in temperature.

Not all of the particles of a substance have the same kinetic energy. At any given time, the kinetic energy of the particles can be represented by a distribution. Some atoms or molecules have a lot of kinetic energy and move very fast. Other atoms or molecules have a little kinetic energy and move very slowly.

Temperature is a measure of the average kinetic energy of the particles in an object. When temperature increases, the motion of these particles also increases. Thermal energy is the total energy an object has due to the internal motions of its particles.

Our existence, as well as our ability to touch and interact with the universe around us, is governed by the collisions of atoms and molecules. The constant jostling and vibrating of these particles give us heat, light, and life.

When they collide, interesting things can happen. In most proton collisions the quarks and gluons inside the two protons interact to form a wide array of low-energy, ordinary particles. Occasionally, heavier particles are produced, or energetic particles paired with their anti-particles.

If “touching” is taken to mean that two atoms influence each other significantly, then atoms do indeed touch, but only when they get close enough. With 95% of the atom’s electron probability density contained in this mathematical surface, we could say that atoms do not touch until their 95% regions begin to overlap.

Particles are, by their nature, attracted to particles with an opposite charge, and they reject other similarly charged particles, like magnet poles, says quantum physics. Such a practice prevents electrons from ever coming in direct contact. Their wave packets, on the other hand, can overlap, but never touch.