* Electromagnetism: The force of attraction or repulsion between charged particles. It is responsible for the interactions between atoms and molecules, and is the basis of all chemical reactions.
* The strong nuclear force: The force that holds the protons and neutrons together in the nucleus of an atom. It is the strongest of the four fundamental forces, but it only acts over very short distances.
* The weak nuclear force: The force responsible for certain types of radioactive decay. It is responsible for the transformation of one type of subatomic particle into another, and is responsible for the creation of the elements heavier than hydrogen.
