The once ultimate particle of an element, believed to be as indivisible as its name indicates. Discovery of radioactivity demonstrated the existence of subatomic particles, notably protons, neutrons, and electrons, the first two comprising most of the mass of the atomic nucleus. We now know that subatomic particles are further divisible ino hadrons, leptons, and quarks.
Origin
[G. atomos, indivisible, uncut]
activated atom
Bohr’s atom
excited atom
ionized atom
labeled atom
nuclear atom
quaternary carbon atom
radioactive atom
recoil atom
stripped atom
tagged atom