Particle Theory of Matter

A particle is a minute piece of matter, such as a molecule.

The idea that all matter is made up of particles was first considered about 2400 years ago in ancient Greece. The particle theory of matter is so useful it is now universally accepted. John Dalton and Democritus were two men born more than 2000 years apart in two different cultures. Democritus was born in Greece, and Dalton in England. While thinking about matter and its nature, they both arrived at the same conclusion; all matter is made up of particles. During the two thousand years between the existence of these two people, this idea was largely ignored.

The particle theory, a scientific model of the structure of matter, is a widely accepted theory that can be summarized in the following five statements:

1.) All matter is made up of extremely tiny particles.

2.) All particles of a pure substance are the same. Different substances are made up of different particles. Each pure substance has its own kind of particle, different from the particles of other pure substances.

3.) There are spaces between the particles. These spaces vary depending on the state of matter.

4.) The particles are always in motion.

5.) There are attractive forces among particles. These forces are stronger when particles are close together.


According to particle theory, pure substances are materials made up of one kind of extremely tiny particle. An example of a pure substance is gold.

Explanations:

1.) These particles are the smallest pieces of matter that can identify a substance. If you take a substance and break it into successively smaller pieces, eventually you will come to the smallest piece – a particle. If you are able to break a particle further, you change the substance into something new.

2.) Gold particles are all the same and are different from silver particles. There is no difference between water particles found in Aurora and water particles found in New York (or any other place).

3.) In a solid, particles are close together and move slowly. In a liquid, particles are further apart and are freer to move around and move faster than a particle in a solid state. In a gas, particles are far apart and move quickly.

4.) The particles always are moving. The more room and energy a particle has, the farther it can travel.

5.) The attractive forces are strongest in a solid, because particles are closer together. They are weaker in a liquid since particles are farther apart, and weakest in a gas because particles in a gas are far apart. Also, some particles are more attracted to one than another. For example, chlorophyll particles are more attracted to each other than to a water particle, which explains why you cannot wash a grass stain off of clothing with only water.


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