 The modern atomic meaning was proposed by Ernest Rutherford in 1912.The adoption of the term "nucleus" to atomic theory, however, was not immediate.In 1916, for example, Gilbert N. Lewis stated, in his famous article "The Atom and the Molecule", that "the atom is composed of the "kernel" and an outer atom or "shell""

The nucleus of an atom consists of neutrons and protons, which in turn are the manifestation of more elementary particles, called quarks, that are held in association by the nuclear strong force in certain stable combinations of hadrons, called baryons.