Overview of the Study of Matter

By Ron Kurtus (revised 14 March 2016)

A major aspect of Physics concerns the study of matter and how the various forms of energy affect matter.

There have been several theories about what matter consists of and how it behaves. Matter can be broken into particles and even waves. There are different states of matter, depending on temperature and pressure on the material.

Questions you may have include:

• What are the theories of matter?
• What are the particles of matter?
• What are the states of matter?

Theories of matter

In an effort to understand matter, scientists came up with several theories of what matter consists of. Originally, matter was defined simply as something that takes up space and has mass. It is all the stuff around us.

On closer examination of matter, at the microscopic level, it was found that matter was not continuous but was made up of tiny particles in motion. This brought about the Molecular or Kinetic Theory of Matter.

The Atomic Theory of Matter states that matter consists atoms that make up the molecules. The Quantum Theory states that the particles of matter can also be in the form of waves. This is also known as the Wave-Particle Duality.

Particles of matter

Particles of matter start with molecules, which are made up of atoms bound together by electrical forces.

It was thought that atoms were the smallest units of matter and were indivisible. However, further experiments showed that atoms were made up of even smaller subatomic particles: protons, neutrons, and electrons.

It was then found that protons and neutrons where made up of even smaller particles called quarks. Also, a number of other particles were discovered that were not part of the atom.

To add to the confusion, experiments showed that electrons and the other subatomic particles can act as if they were waves. This was called the particle-wave duality.

Finally, although we call them particles, envisioning tiny little balls, there are theories that they exist as strings or clouds.

States of matter

Certain materials can exist in several different states or phases, provided the molecules do not break down or result in a chemical reaction. These phases depend on the temperature and external pressure on the material. These states are:

• Solid
• Liquid
• Gas

Liquids and gases are considered fluids. They have a number of characteristics in common.

There are also some exotic states of matter:

• Plasmas
• Bose-Einstein condensates

Summary

In the study of matter, there are theories about what matter consists of and how it behaves. Matter can be broken into particles and even waves. There are different states of matter, depending on temperature and pressure on the material.