Why do atoms have different isotopes?

Plenty of elements have a few combinations that are stable, so those elements have several observable isotopes. Usually one isotope is predominant, though. Chlorine for example has two major isotopes, Cl-35 (~75% abundance) and Cl-37 (~25% abundance). read more

The different isotopes of an element have the same number of protons basically. The number of electrons can also be common in all but it has a certain condition. An Isotope can be ion and if and only if the isotope is electrically neutral, it has same number of electrons too. read more

Best Answer: Atoms have different isotopes because their nuclei have differing numbers of neutrons. Helium has 7 known isotopes, ranging from He-2 to He-8, but only 2 of these are stable, He-3 and He-4. He-2, the lightest possible isotope decays to 2 protons, or H-1 with a half-life of 3*10^-27 seconds. read more