Why aren't isotopes in the periodic table?

Isotopes of the same element all have the same atomic number, i.e. number of protons. This also represents the number of electrons of an electrically neutral atom of that element. read more

Because modern periodic table is arranged according to the atomic number of the elements. Whereabout isotopes have same atomic number (but different atomic mass). And that's why isotopes don't occupy an indiviual position in periodic table. read more

Because of the proton/neutron mass difference, we still wouldn't have integer values. Carbon 12 has a 1:1 ratio of protons to neutrons. In the absence of any difference in binding energy per nucleon, any isotope with a 1:1 proton to neutron ratio would have an integer atomic mass, but an isotope with any other ratio would not. read more