Tesla Coil Basics Matter is all material in the universe. An atom is a minute unit of matter which is formed by a combination of subatomic particles.
Subatomic particles are particles smaller than an atom.
Three types of subatomic particles occur in atoms all around us. These are the proton and neutron, which form the nucleus at the center of an atom, and the lighter electron outside the nucleus. A proton has a positive electrical charge and an electron has an opposite negative charge. A neutron has no charge at all. An ion is an atom with a number of electrons unequal to the number of protons.