- Electrons - carry a negative charge and there are always the same number as protons; they orbit around the nucleus
- Protons - carry a positive charge and are arranged in the center of the atom, the nucleus, with neutrons; the number of protons defines which element the atom is.
- Neutrons - particles with no overall charge that are sited in the nucleus; atoms with the same number of protons but different numbers of neutrons are known as different isotopes.
In 1930, Edith Keeler gave a speech to the people in Twenty-First Street Mission, that Humans would soon be able to control great energies, maybe even the atom. Spock remarked, that she envisioned atomic power years before it was developed. (TOS: "The City on the Edge of Forever")