Does more neutrons in an isotope make it more or less stable? I got two contradicting sources. I am also quite confused overall about the whole isotope business. The definition of an isotope is that it is an atom with the same number of protons but different number of neutrons. For example, carbon isotopes go from 8 to 22 as far as wiki says (https://en.wikipedia.org/wiki/Isotopes_of_carbon) and it also says 12C and 13C are both stable, and all others are unstable. But, first of all, isn't 12C not an isotope, since the number of protons is the same as number of neutrons? Secondly, it seems that there are unstable 8C, 9C and so forth and then 14C over to 22C must be unstable as well. So it seems to me that greater the number of neutrons doesn't exactly mean either more or less unstable, but rather that the closer the number of neutrons to protons the more stable the atom. Why would these books/internet/teachers try to say either of these incorrect statements? Thanks for help.