The range of the number of isotopes that chemical elements can have is 3 to 36.
The element with the least (3) number of isotopes is Hydrogen, while the elements with the most number (36) of possible isotopes are Xenon and Cesium.
Isotopes are different forms of the same element, in which the number of protons in the nucleus of the atom is the same for the different forms, but the number of neutrons in the nucleus is different.