Why do we have isotopes?

Isotopes are simply elements with a different number of neutrons. They exist and are found because of scientist's desires to extend the periodic table. By bombarding elements with higher atomic numbers with radiation, electrons, alpha particles, etc, we create different isotopes of elements that have a different amount of neutrons than the element listed on the periodic table. Some of the isotopes decay into more stable compounds, or even elements that are currently listed on the periodic table.