Radiation comes from atoms that are in the process of changing. The atom is the smallest unit that shows the chemical behavior characteristics of an element . The center of each atom has a nucleus that contains protons and neutrons. Protons are positively charged particles. Neutrons, which have no electrical charge, hold the protons together.
Electrons are negatively charged particles.
The electrons surround the nucleus and travel in orbits. There is a theory called The Rutherford-Bohr Theory of atomic structure. It compares the atom to our solar system. At the center of every atom is the positively charged nucleus, which could be compared to the sun in our solar system. The electrons move around the nucleus as if in orbit.