An atom a fundamental piece of matter.
An atom itself is made up of three tiny kinds of particles called subatomic particles: protons, neutrons, and electrons. The protons and the neutrons make up the center of the atom called the nucleus and the electrons fly around above the nucleus in a small cloud. The electrons carry a negative charge and the protons carry a positive charge. In a normal (neutral) atom the number of protons and the number of electrons are equal. Often, but not always, the number of neutrons is the same, too.