No, not all atoms of the same element are identical. Contrary to Dalton’s theory — that atoms of the same element are identical — scientists discovered that atoms comprise smaller sub-atomic particles. Further experiments revealed fundamental particles beyond neutrons, protons and electrons. Although an atom is the tiniest particle of an element that retains the element’s intrinsic properties, all 92 stable atoms are composed of only three smaller, more fundamental particles.
Dalton’s theory led to further developments and new fields of experimentation. However, he only probed the chemical behavior of objects and assumed that all atoms of the same element are identical. What he didn’t know was that it was possible for atoms of the same element to have different numbers of neutrons and different masses; thus, not all atoms are identical. Atoms of the same element that have different numbers of neutrons are known as isotopes. The difference between isotopes is important, because their behavior at extremely high temperatures and pressures vary. An example of how isotopes can affect atoms are nuclear fission reactions. An atom with the same number of protons but different number of neutrons will produce different chemical reactions. Currently, scientists know of 118 different atoms. Atoms are unique physically and chemically. The electrical charges of the electrons and protons of atoms govern most chemical interactions.