Atom bombardment ejects what appeared to be hydrogen nuclei. By 1920 he had accepted that the hydrogen nucleus is a distinct particle within the atom and named it proton. Neutrons have no electrical charge and have a free mass of 1,839 times the mass of the electron, or , the heaviest of the three constituent particles, but it can be reduced by the nuclear binding energy. Neutrons and protons (collectively known as nucleons) have comparable dimensions—on the order of —although the 'surface' of these particles is not sharply defined. The neutron was discovered in 1932 by the English physicist James Chadwick.
Empire of the Atom bodily" from the plot of "I, Claudius". A genealogy chart of the ruling family of the Empire of Linn is included. Van Vogt based "Empire of the Atom" largely on the plot of "I, Claudius" by Robert Graves, putting it into a science-fictional setting. The work was originally presented as five novelettes published in "Astounding Science Fiction" between May 1946 and December 1947. Some time, a little over 10,000 years from now, a noblewoman gives birth to a deformed child, a consequence of having been accidentally exposed to radiation from one of the temples of the Atom Gods. The baby