- Protons and neutrons seem to be made of even smaller particles called quarks.
- While protons, electrons and neutrons seems to last for ever (the ones in your body were made in the big bang thirteen billion years ago), there are particles that play a role in holding atoms together that are only last for about a million million million millionth of a second.
However, to illustrate the principles of quantum theory we can ignore most of the other fundamental particles that have been found, and concentrate mainly on protons and electrons. There is one other important particle, called a photon, which is actually a particle of light. We will get to know more about photons later.
NEXT LESSON: protons and electrons in atoms