The Particle Theory of Matter A theory is an explanation that is based on the outcome of many of many experiments. After centuries of studying matter scientists have created the Particle Theory to explain many of the properties of solids, liquids and gases. The Particle theory of matter has five main parts, which are summarized below. 1. All matter is made up of extremely tiny particles, too small to be seen with the naked eye. 2. Each pure substance has its own unique particle. Particles of different substances are different and have different properties. 3. The particles are attracted to each other. The closer the particles are, the more they are attracted. Substance A Substance B 4. The particles are always moving. The more energy they have, the faster they move. The ways the can move are to vibrate, rotate, and move from place to place. 5. At higher temperatures, the particles have more energy on average than at lower temperatures, and therefore move faster.