The atom comprises a central nucleus containing protons (positively-charged) and neutrons (with no charge). The electrons (negatively-charged) revolve around the nucleus in different imaginary paths called orbits or shells.
Atoms are made of extremely tiny particles called protons, neutrons, and electrons.
A proton is a subatomic particle with a mass defined as 1 and a charge of +1 (positive charge). A proton is indicated by either the symbol p or p+. The nucleus of every atom contains protons. The number of protons of an atom of an element is its atomic number. The nucleus of a hydrogen atom or the H+ ion is an example of a proton.
The neutron is a subatomic particle with a mass of 1 and charge of 0. Neutrons are found with protons in the atomic nucleus. While the number of protons in an atom determines its element, the number of neutrons determines its isotope. Nuclear fission and nuclear fusion are two nuclear reactions that release large quantities of neutrons. A neutron is considered a type of fermion because it has a spin of 1/2.
An electron is a stable subatomic particle with a negative electrical charge. Each electron carries one unit of negative charge (1.602 x 10-19 coulomb). A common symbol for an electron is e–. Electrons are found free in nature (free electrons) and bound within atoms. The mass of an electron is 9.10938 x 10-31 kg.