In time, the nucleus of the atom, around which the electrons orbit, was found to consist of larger particles — neutrons and protons. The 88 different kinds of atoms, or elements, that occur naturally on earth are basically the same size, but they vary in weight because each has a progressively larger number of these three basic particles.
Vēlāk tika noskaidrots, ka atoma kodols, ap ko riņķo elektroni, sastāv no lielākām daļiņām — neitroniem un protoniem. 88 dažādie atomi, kas sastopami dabā, ir aptuveni vienāda lieluma, bet tiem ir atšķirīgs svars, jo tos veido dažāds skaits minēto trīs daļiņu.