Atoms are the building blocks of matter and they are composed of three particle types.
The central core of the atom is called the nucleus and it contains positively charged particles called protons and neutral particles called neutrons. The movement of many charged particles in the same direction is called an electric current . Charged particles flow most easily through conductors , such as metals, or through some liquids, such as salt water. Electrons in metals are loosely attached to the atoms, so they can move easily. Insulators , on the other hand, do not conduct electricity well.